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'm'*^^^^^^^^^^^^>^^^^^^i^^^^^^^^^^^^^^*^^^^^^^^^^^

aiF'TT ow

GEORGE C. MAHON, Esq,

TO THE LIBRARY OF THE

UNIVERSITY OF MICHIGAN.

^■^■^■^■tl^^^^^^^^^^i^^^^^^^^^wc

34,7

A

TREATISE

ON THl

EXTERNAL CHARACTERS

OF

FOSSILS.

TRANSLATED FROM THE GERMAN

OF

ABRAHAM GOTTLOB WERNER,

«OVV8ILLOR or MIWKS, PROFEMOR OP Ml:7ERALOOT, PUBLIC TEACHER OP

TB£ ART or MINING IN THE MINE- ACADEMY OF PREYBf^O,

AND MBMBfiJl OF SEVBRAL LEARNED SOCIETIES.

BY

THOMAS WEAVER.

»««9(»h#HQ«^

DUBLIN :

»aillTED rO% M. N. MABONy IO9, GftAFTON-BTREET, ANO SOLB IN JLOMDON BT MKI811S. LOMI^IiAN, BEES, HUR4T ANI> Q%Ut,

FA'^BB NOSTRR ROW.

1805.

TO

RICHARD KIRWAN, ESQ,

PSEfflDEMT OF THE

ROYAL IRISH ACADEMY,

FELLOW OF THE ROYAL SOCIETIES OF

LONDON AND EDINBURGH, &c. ftc.

THIS TREATISE

pi TBI

EXTERNAL CHARACTERS OF FOSSDLS,

IS INSCRIBED

IN TESTIMONY OF THB HIGH RESPECT

OF HIS FAITHFUL AND OBLIGED SERVANT,

The Translator.

Poblby aSA Sept 1804*

fc

n\

i'

ADVERTISEME:fJT

OF THB

TBJNSLJTOIL

THE name of Werner is so celebrated^ and his reputation so well established, in every country in which the public attention has been directed to so interestiog a study as tl^ of the Natural History of Fossils— that ^ to present a translation of his ingenious Trea-

tise on the External Characters of Fossils^ might seem syifficient to ensure to it a £ivour- able reception.

^ Mr.

u

Mr. Werner published his work in the year 1774. Since that time a period has elapsed ia which rapid strides have been made in every branch of Mineralogy; and, as it might be expected^ considerable improvements have taken place in the Treatise on the External Charac- ters of Fossils, Aware of such, the lovers of Mineralogy in Germany have frequently called pn Mr, Werner for a npw edition of hi? work. His numerous avocations have hitherto prevented a compliance with the wished of the public j and the period of its appearance is perhaps still remote. Under these circum- stances, the Translator, desirous of completing the integrity of the work, has had recourse to other sources to supply the deficiencies of the printed original. These are principally— copies of Mr. Werner's manuscript corrections and additions as circulated among his pupils, notes taken during his lectures in 1791 — 1792* ana

• ■ ■ •

the

I

f I

uc

file Mineralogies of his disciples Wiedenmann and Emmerling ^ and to illustrate the extra- peons forms qf fossils, the Manual of Natural Historjr of Professor Blumenbach has beipi consulted^

In the denominations given to the Charac- ters and to the Fossils employed in illustratioa of them, the Transktor has commonly followcit Mr: Earwan ; to whose valuable labours Minera« logy m general is so much indebted*

The Characters are tabularly arranged ia the system with the corresponding Qerman, presenting a connected view qf their relations to each other ; and of the Fossils an alpha- betical index is added^ accompanied l>y their German synonims, and with references to the several sections in which they are employed as illustrative examples of the External Cha-

racterst

la

\

lot order to * elucidate the stibject of crysCaBI-' zations, two Plates of cryttalline forms are added, and explanatioos of the figures an- nexed.

In fine, the Translator hopes that the Trea^ tise on the £;ctemal Characters of Fossil? now appears in a more entire forq) tl)an has hitherto been made public.

PREFACE

PREFACE

OF THE AUTHOR,

In verih ffon stmtufaclks ut eonvmiamus In re.

BY the title of this small work the reader b promised a Treatise on the External Cha- racters of ' Fossils J I have, however, takcii

the liberty of rather exceeding its , limits, ex-

« •

pressing at the same time my ideas on the

deficiencies of Mineralogy in general, and oa

the meaqs of removing them.

Among these I consider as one of the principal, the neglect of descriptions of fossU$ according to External Characters ; and as I hold such descriptions to be most needful in Mineralogy, my attention has been chiefly directed to the consideration of the External

Characters

xu

Characters of Fossils, and hence these form the principal subject of the present work.

I have accordingly ^I^ewn that these Cha« racters are not to be applied as hitherto to the systematic distribution of fossils; but merely to determine the conception of their Extejtior, and to fix the method of describing them: that the External Characters hitherto employed by Mineralogists are very indetermi- nate ; and that the perfection and utility of the External Descriptions of Fossils depend on the complete definition, and arrangementa of the flxtemal Characters*

To remove these deficiencies in some mea-* sure, I have not only endeavoured to deter* mine in general the proper conception pf the External Characters of Fossils, and to define each in particular as accurately as in my power ; but I have also pointed out the me* thod of constructing complete} and duly ar«

ganged,

3dil

iflnged, descriptions founded on the characters. Andy for the sake of greater clearness and precision, I have illostrated the \(rhoIe by examples.

I have -also added a condse history of the External Characters, in which those Minera* fegists alone are noticed, whose works, m rdation to them, are remarkable in one pomt or another.

It will be found that I have considered Mineralogy in several points very dLSerently firom the usual practice ; whether justly, I leave to the impartial decision of intelligent and discerning Mineralogists, particularly as I conceive my reasons suffidently detailed.

I shall rgoice and deem my labour rewarded,, should my small work be honoured with a full enquiry ; or should I be refuted on good grounds, where I have erred in departing from generally received opinions ; or where I have

proved

XI?

proved correct^ receive assistsitice to ks farther improvement for the advancemeat of Mineralogj.

But, should Mineralogy be hereafter culti- vated on the principles now proposed, some might indeed spare us the perusal of their writings; since to execute a work on Mine* ralogy vironid no longer be so easy a task, and would require more labour and acutenesf in observation. A work conducted otf tiiis plaA would prove more usefiil and beneficial than all those which have hitherto appeared, par- ticularly if executed by an able, experienced^ and attentive Mineralogist. * In this case, should we meet with a fossil of which we had no knowledge ; nothing more would be requisite, in order to leara its name and

to

* This was accomplished in part by Mr, Werner himself in his edition of Cronst€dt in 1780 ; and the sane prific^ pies have been since followed in the Mineralogies of LenZt Wiedenmano) Emmerling» Estner, and Brochant: bat far a complete exposition of the Wernerian doctrines we may look to the systematic work of Mr. Jameson^ of ^hich the l«i Vol, has recently appeared. Tr.

XV.

tp kaaw what species It belonged, than ta detemuoe its external conception by the discorojr of the £xternal Characters, and to refer ta this conceptioa ia the sjsteoi': or shMld we find fossils mentioned in the sj^ tern, which we had never jet seen ; com*- plete external conceptions of them might be immediately derived from their descriptions, by which they might be recognized when- ever occurring to us, without troubling our- selves as hitherto with uncertain, and fre- quently groundless, conjectures.

I now await the reception which this small work may meet with from the mine- ralogical public. It has at least the merit of a good intention. Should it receive ap- probation, I shall hold myself bound tm coommiiiQate m future also my mineralogical labouR.

Lastly,

:Kvi

JLastly, I trust that the liberty \i^hicii I have taken of expressing my sentunents on the writings and opinions of others^ will be thought justified by the good object which I had in view ; which was no other than the advancement of Mineralogy*

CONTENTS,

CONTENTS.

INTRODUCTION. 0/ Mineralogy

in general - - - - {. 1— §• ^2.

CHAPTER!. Of the characters qf/os^ sUs in general y and of the fre-^mi" nefice and utility of the External Characters - . - 5- 13— §. 21.

CHAPTER n. History of theExter^

nal Characters of Fossils - §• 22— §• 31.

CHAPTER ni. Of the definition qf

the External Characters of Fossffs §; 32— §• 40. CHAPTER IV. Explication of the External Characters of Fossils. Of the Ist. Common Generic Cha^

racier. The Colour - $.41— §.62.

Of the Hod. Common Generic Cha* racier. The Cohesion of the > particles . . . §« 6S-^. 67.

I. Of the partictdar generic cAarac^^

iers of solid fossils • ' ^ §. efi-r^. 70.

ChAKACTERS for TIt£ SICHT»

Of the external appearance §. Ill

1. Of the external form - - {. 72 — $. 163. ^* Of the external swcface • $, 164—^. 172.

b Z.Of

Xrill ' OONTJKNTS.

Z. Of the extemallusire - J. 173—}. l«t.

Of the interna app¥^A9^AKC.£ $• 18X«

Of the appearance of the fracture §• 132.

'^. Of the internal lustre - }. 183.

5. Of the fracture - - - $. 184— §. 197.

6. Of the farm of the fragments }. 1 98 . Of the appe^jaace f4 ^ flistin^t - - . ,

pofpcretions_ .. - .- • . * <• l^^-

7. Q/* thef&rm ^f tic distinct c(m*

cretion^ • ♦ $• 2P0*^t* 805.

S. Of the surf^^cqfsef^arfifUj^ ,•* 4- ^^*

^. Qfth^l%streof ^aration . - $• J207.

Of the g£9£]L4L afpear^AN^^ (• 99f •)

IP; <?/!"/** tfansparencjf - $. SI0iH»-4' «14»

11. Of the streak ^ ^ (• >l<*>

11?. ^/4f 5«im • r |, «W.

ChARACTEB^ FPR the T9VCH.

13. Of the hardness - - §. 217.— §. 22S.

14. Of the selidity - - §.224.

15. Of the frangibai^ - • §. 225.

16. Of the JkxzHliiy - - §• 22«. \1\ Of the adhesion to the tongue - §.227.

•

. .C1JAB.ACTER.S FOR THE KBARINC.

\i. Of the smmdr - - J. 228.

II. Of ^he particular generif chanfQ'

\ tersof friable fossUs • §. »«9-^. ftJCV \. Of th^ external form - •• 4v^?';

2.0/

CONT£Nt^ fix

2. 0/ the lustre - - • i» 2J«.

3. 0/ the appearance of the

particles ... §. ^33.

4. Of the stain - - - §. 234.

5. 0/ the frioMiijf - - §. 235. III. Of the particular generic chm^

racters of (LxxiAixmAs - §. 236.

1. Of the external form - §. 237.

2. Of the lustre - . - |, 233.

3. Of the transparency . \ 239.

4. Of the fluiditif - - |, 240*

5. Of the wetting qf the fingers §. 241 . Of the Hid. CbTn^Acm Generic Cha--

rtfc^^. Tbe Unctuosity §. 24^.

OfAe IVtb. Commm Generic Cha^

racier. The Coldness ^ §* 243*

<y the Vtb. Common Generic Cha^

racter. The Weight $. 244.~§. 2«f4. Of the Vlth. Common Generic Cha^

racter. The Smell - §. 255.

Of the Vllth. Common Generic Cha^

racter. The Taste - §. 256.

Conclusion of the Chapter - §. 257.

CHAPTER V. Of the External De^ '

scriptUms of Fossils - §; 258.^. 264. Description of Grey^Copper^Ore.

Green-Lead^Ore. Red'Lead-Ore. Mica. Common Talc.

b2 Xki^ptioa

XX CONTENTS.

Description of Specular Gypsum.

Vitreaus-Silver-Ore. Vitrtous-Capper-Ore.

1. Compact.

2. Foliated. Tinstone.

1. Common.

2. Fibrous^ Copper-Pyrites. Arsenical-Pyrites.

\. Common. 2. Argentiferous. Tin-Pyrites. Of the chemical y physical^ and empi- rical characters - §. 265.— -§. 265« SYSTEM of the External Characters

of Fossils^ INDEX of the Fossils employed in il- lustration of the External Cliaracters. EXPLANATION of the fgtires in Plates 1. and 11. '

A TREATISE

A TREATISE

OM

THE EXTERNAL CHARACTERS

OF

FOSSILS.

INTRODUCTION.

Of Mineralogy in General. §.1.

A.LL sciences are valuable; differing only in thii respect, that some are more extensively useful than

others, or more immediately related to common life*

§.2.

One of the most generally useful, and nearly in- •dispensable to civil society, is Mineralogy, or the natural history of fossils. Its utility to the Miner, Smelter, Physician, Chemist, Natural Philosopher, &c. is too well known to need particular notice here 9 and it would be contrary to my .present design to hold .a panegyric on this science.

§.3.

Of the several branches of Mineralogy *, Otyc- UgJiosy is unquestionably the most important ; espe»

cially

* To the readeTi tmacqusuated with Mr. Werner'f method of treatiiig Mueralogy, it may not be useless to observe thtt, consider* ing this science in difierent points of riew, he has accordingly dis* tribtttcd it into ftrt diitiact braaches, treatiiig of each lepuatcly^

«9

2 Of Mineralogy in Generat.

cially as it forms the foundation of Geognosy and Mineralogicdl Geography.

§4.

Since the value of tiii«iScienoe became more gene- rally known (a period of near forty years, when it first began to floaviek)> it ha» been cultivated by many learned, able, and patriotic men with consi- derable ardowr, and by several with* great success : — among the latter I will only mention Henkel, Lin- nseus, Wallerius, Bomare, and Cronstedt. But the genei^al labours in this field of science are fuMy evinced by the multiplicity of systems which have been produced, the number of which are annually increased at least by one additional, independently of small tracts on particular subjects.

§. 5.

H<yweviBr, tht9 multiplicity of systems of Minera- l^E^y ^^ rathev of Oryctognosy, is a convincing proof that the science has not yet made that pro- gress which is so much to be desired ; since several of these systems contain nothing more than the title, and an incomplete and incorrect catalogue of fossils.

§. 6.

9B Ofjtt$gimy^. JUiiurmltgual CbeaMtfyy Getpiosyy Miturah^ud Gm* gTBpby^ and Etmumital Muurahgy. A brief ezpcAition of the ligai* alfintion of these terms may not be unacceptable. ' Oi jrfyniiiy tcachn ua to know'fossil»,xo recognise themr whcn«ver tlwK occur to us. For thi* purpose it exhibits the aubjccts.of the Ittincnl kingdom to our inew acrang^ in an »rder corresponding v .9mdf a^posable withr that of thfir mfmitis0^ and distinguished from .<ach other by a^r^ptUAt demmiuuAhnt and by determiMote and Jfjuud

♦ • ■ . "

J. 6.

Wben I op^i a work oo Oryctognosy, it is with . an intention — either of obtaining a general knowledge of this science; or of acquiring ^ in f articular j the complete conception of a fossil which I know only by name; #r of learning in re^speet sf k fossil it>hich I.k(^fmM, mi vA^e Ketetndl Cbaractefs I h9» disioifcttdi tohaf ir its na^fne^ and whMpUbci . U^copiisin tile sysl^fn effdsMs. If a work for the t^&3t: pfti^t atiswe¥s th^sa purposee, k ttteiy bi t&mtd good; Md if ^Mirejy , peffeet Nov, how

faip- •

*nie ol^ect of MlBcrah^ttl Chemistry ]» the andlysiu of fotttlf*

the dbtdteiy of thtir cdtMSnkeiit prindpl^s; tvlUcli ethiedtfil^' afititiev to each otlier, aad hence form tftc fiiBduiieiital pHnol*. pie of their classification.

Ce^g^Mij treats of the geoeral stnMfture of thd eartTu U ihai^ Q« aeqttflbiteiil ilMi the njamm aild pMrtUtMt Mr of fosiiW* wWv their probable oApn^ relative formation and arrangement in the Earth— with the ruks which compose mountains, an<f which consti* tnte, if not the solid mats, at least the great shell of the Globe — with Ae varkms jtriOa and wins which form the -more particular re- positoriies of fossils^ and' with their reciprocal rcldtioni 19 each s"^

other.

llie province of Mitur^pcat' G§egrap6y is to descrHMfi g^ogfk'apIiS* ciHyf «the occurrence of fossik in different countries* It describea the general surface and great outlines of a country, the several kinds dF racks which form iu mountains xifitE their varlour mutual* re- lations to each other, to the distinct strata which are imbedded in them, and to the veins which intersect them, with detaili^ notices' of the fossils which these severally bear.

The object of Economical MiHeralogy is to shcw the various econo- mical purposes for which fossils may be employed. It treats ol" them la an order corresponding with the several uses to which they are' applicable, attending to those particular properties which qualify them for the operations of the Potter, the Class-malLeri the SmcUjcr, tiie Painter, the Architect, the Farmer, &c, Tt.

4f Of Mimeralogy in Gmtral.

far our Orycfcognostical works bave hitherto attained this end, and hence what progress the sciesM has made toward perfection, I leave to the decision of any impartial person. '

§. 7.

There are two obstacles which principally ob* struct the progress of Oryctognosy : . the first is, that many, in treating of it, confound it with other sciences, and neglect the essential part of the science itself, by dwelling upon that which does not pro- perly belong to it, or which at most should only be added in a note.* The second and principal is the division which subsists among Mineralogists; one party endeavouring to found the whole science on the External Characters^ and another, on the contrary, attempting to accomplish every thing by means of chemistry, and by the discovery of the constiitient principles, of fossils.

I shall not at present enter so far into the subject as to adduce arguments in opposition to one or

the

* I am by no means dispoicd to reject in this place those useful relations which respect the Bedit and firmatim of fusiU^ their geiigra^hy and wei they may in the meanwhile, during the formation of the sciences to which they respectTvery belong, be added in Oryctognosy with great propriety in a note at the end of each species of fossils. I only say that, in attending to these cfonsiderations, the essential part of^the science ought not to be neglected. Besides it must be obvious to every person that a work on Oryctognosy is not the proper place for a Treatise on tht Art tf Assayings for DttcriptUm of Mme*^ Operations in Smtlt'-

Of Mineralogy m Gmetd. s

die other ofmiion. I will only remark that neither parfy OMMiders, diat to class fossils in a ysiemy and io know fossils from a consideration of their Exte^- rWy are two distinct things, and that to attain either end, yerj different means must be emj>loyed. In fact the impraclibility of either plan alone is eyident; since, of the former party, each felt the necessity of applying the chemical constitution of fossils to his system : and all of the latter employ- ed in some degree the External Characters to de- scribe the species of fossils, and to distinguish their yarieties.

Wallerius* was the first who thought of uniting these two sects, and for this purpose proposed (by which he also thought to approach neater to the tiature q{ the subject,) that though in the distribu- tion of fossils the chief r^ard should be bad to their constituent principles, yet the External Cbiw racters should also be employed as subsidiary ; and in sudh a manner that the orders and genera should be principally determined by the constitution, but the species rather by the External Characters^

Gerhard t has lately presented a plan for form- ing* a correct and natural mineral system, in which he also endeavours, in some measure, to unite the

two

*l>e Syttematibiu mineralogidt et systemate mmenlogico rite condendo. Holmic. S. X76S. $• io% aad 103.

-f BcyifSge sur Chemie und Ocichichte dci Miiicral*JUiclUy i. ThciL Berlin. 8. 2773. S. 13.

twd djphtofM. ' He propose to detenaM the dmsesy iriir^y and siction^ <$f fosdHs by tfieif ^^mAhMAw^ rtA &dt >eAr/uf»^ in ^bemioafc expcfriBUMiits, «wl if j^Mrfble^ tbe jr^M^<z «nd* ^(fmx also ; but if dw nMte of dei^ihtofltioii: Ai^vAd be fomid idsofici^lkt hr Ae tw» Uttoiv, to employ likewise the Estcmd tfk^roKiefSy and principaHy the* gtruecore and live dohcMK^ii 6t Ae paopticles.

• «

§. Id.

I must confess, the two forementioned Mine- ralogists approach very near to the nature of the. subject, and particularly the latter ; yet their opinions appear to me rather indeterminate. My dlliitioil i»; that tkt damfieetium of foBsUs sheudd- be J^nded' on their eonstitutim, etiendh^ fiaf their ^ifecies^. For a mineral system has no otbe* object than to determine the naturai order or succession ef the dififetene fo^iii ; anfd the move iccorately this is dMomphshedy the more perfect tr>II ij»tf mineral system be : now, the essential iifferefuet effessih are contained in their c^nstUuthn (as in toimals and plants, in tiheir conformeUion^ which extendto their species); the spe'cieS'of fossils, there* fore, should also be classed according to the prin- eiple of their essential differences, t . e. according to th^ir canstitidion.*

§. 11.

* Partly by way of proof, p^irtly of illuttration, of the foregoing paragraph, I wiU idd a te^r obsev^tfotir on the clatsifiratioii or d»sff<bttrloiL U iMtttraA liodiet k gcilcrsl. Whea we with to dass

natural

Of Mvnerahgjf hi General. 1

'to the obstacles which have retarded the ad- iraocelkient of Oryctognosy might be added the want of deftnitioti in the denomination of fossils ; arisidg' principally from the introduction of new provincial

denomU

■ititfal bodies^ <ft which U the aaaie thing, to dctennmc their tuam nd wdtir^ we mugb amettarily «eek toeit pruuipU \3ff which this de-^ •rtmi— fion thail bo rei^kied-; but Hai^prutafU miut likewise ezise m the natmn ci these bodies^ beciiiise their order or succession i» •or be Mttiifal': and* as we have further to determine by it» how dif«' it» bofderingon, or passing into» each othnr, tu:cordiflgto their » these bodies are (for this is aalled themomat order/ ; it must, Kfaewise be the principle of their diflereaces : for, according aa» these relations are dtflbrent» bordering on, or passing into, each •ther; so ab^ave the bodies which stand u» these relations:* Imee these mdaikm must be the single and only principle by whioh^ we aie to determine the ord^ op succession of natural bodies* We lte«e now to enaminoi where these nlatMte occur in natural bodies^i' but here we find >• difference in them, for they resolve themselves BtD two principal kinds, of which, the relations of the one exist aa ilvir mw/ftrsMahwr, or oiode of aggregation i but thofeof the otbcTt itLtbeir te/utitiOion^ or combination of their constituent principles : the foffmcp inelilides- animals and plants, the latter the substances of the fossil and atmospheric kingdoms : — ^it is* true both are, as natural hadlcs» aggre^itedy and their paru chemically constituted ; but the forttoer are aggregated of parts diiFerent from each other, wliich we. oattorgadlv and in which their relations also exist : the latter, oh the cesmaif, are aggrQgatcd of wholly simple and uniform parts, and their relations, therefore, cannot exist in their aggregation ; buft as tfiey are really different, i. e. possess really diflvrcnt relations, tfasic mkufr occur elsewheier and, a» already observed, most neoQi<> •oiily be ftmnd'in their ctmHttOiom. But that this is the real .state o€ Ao ease may be coUeoted from this ;— 4f a body be taken from cither ^ the two former hiiigdoms, e. ^ a plant, and be divided in any pnssible manner into small parts, neither of these single parts caf» then be said to ccmstitute the same plant, because each of the single |Mvts no lodger possesses the tame rwktim which existed in theii* Awiliwliiation, i. c which exbted in the^ whole, and which consti*

« tutcd

i Of Miner (dog jf in generaL

denominations, or from the use of such as are un- common or merely invented by Mineralogists in relation to their own systems. Several Oryctognosti- cal writers also apply false names to many fossils, either from not knowing them, or fron^ misunder- standing another writer.

This

tuted this whole to this or that plant : here, therefore, the relation must necessarily have lain in the conformation of the plant, because hj its division the relation ceased. If, on the contrary, a fossil be divided, each 6f its -parts, even the smallest part which can possi* biy be obtained by a mechanical division, will still ever be the same fossil; for each of the parts so obtained still possesses the same essential relation, which all the parts possessed in their aggregation ; die relation of the fossils, therefore, cannot have lain in the aggre- gation, because by its division the relation has not ceased. But, if the constitution of a fossil be divided, L e. if it be resolved into its constituent principles, each sin^e constituent principle will no longer form the same fossil, because it possesses not the same relation which was possessed by the constitution, as e. g;— if ^lMVMM/«i- Silver^Ore be resolved into Silver, Antimony, Iron, and Sulph ur ; or Cinnabar into Quicksilver and Sulphur ; neither of these constituent principles can be said to form the same fossil, of whose constitutioa it before formed a part. The relation of fossils, therefore, must necessarily exist in their constitutioo, because the relation ceases by a division of the con^titctton. \

But, moreover, the transition of natural bodies from one into another (and which is the most certain mark of the natural order) ilso proves, that the diiFerent relations of the bodies of the two former kingdoms are contained in their conformation, because such bodies pass one into another merely in respect of their confor- mation ; and that the relations of the bodies of the two latter king* doms, vis.- of the. fossil nnd atmospheric kingdoms, exist in their constitution, because such bodies pass one into another according to their constitution, as c. g. in the fossil kingdom, Native-Silver passes hito Vitreous-Silver-Orc, this into Antimoniated*Silvcr-Ore, and this again into Red- Silver-Ore; accordingly as to the first an ae« eession of Sulphur takes place, to the second an accesuon of An* rimony and Iron, and to the third' an accession of Vitriolic add

instead

Of Mineralogif in General. 9

This evil might in a gpreat measure be remedied by attending in every language, in the choice of denominations, to those Which vrete the most common ; Which had been employed by the best Mine- ralogists ;

Which

instead of Iron. Lattly, hence it also proceeds that we have in- deed sofficienC proofs of the tratuitioms from the animal into the Te- gctable kingdom, and from the fossil into the atmospheric kiugdom; but, on the contrary, no solid argument can nor ever will be pro- duced (notwithstanding what has been advanced to the contrary,) to prove the transition from the animal and vegetable into the fossil kingdom ; because the natural succession of rdations in the former is continued in their conforxiution, and in the latter in their constitution.

However with respect to the order or system of fossils, "the fol- lowing question might still be proposed : ** Since it is certain that ** the Exterior of fossils varies accordingly as their constitution " varies ; might not characters be found in their Exterior, which " should determine the order or succcession of fossils, even as it " exists in the relations of their constitution V* To* this the answef IS ; that although in the External Characters of fossils the dider* Qit relations of their constitution may be perceived, provided botH be preWously determined ; yet the succession of these relations can- not be discovered in them *. and ist. because Nature in cxpressinj^ the difference of the constiturion employs without any order some^ times one, sometimes another character ; and andly. because every External Character proceeds somerimes from an essential difference^ sometimes from a casual variation only : of the impracticability of this we maybe fully convinced by the mineral systems of those who have classed fossils according to their External Characters', in iHiich fossils that are essentially different may be found placed together, and others which are of the same species torn far asun- der merely on accotmt of a casual variation. It is therefore for- tunate for Botanists and 2^ologisto, that in the subjects of Botany and Zoology, they immediately find the relations in the Exterior afthoe bodies, and that when they class thctai aecordiisg -to thcif cooformatioii* or 'the association of their External parts (organs^, they also at the same time describe tMr External Characters,

and

JO Of Minerdogjf in Gener^

Wlucb .were the most ancient;

Which were the most usual^ where the natund history of fossils mostly floorished, and where the language of the country was best spoken;

Which were most suitable to the nature of the fossil, and best adapted to its distinction;

And lastly, by avoiding in mineralogical trans- lations to render the denomiojiAioiw of fossiJs

otherwise

a9<l thut accomplish both together: Mineralogbti, on the con- tnu7» have a different task: fori itt. ui order to daw fotsili^ they onut dcteraiine their constitution by the results of cheinii* cal inTcstigation ; and adly. in order to describe them, they must discover their External Characters. {C^mim^e with ib'u the %tb §.) 1 wSl only further obaerve: ist. that, as it strikes me, JMi* neralogisu have hitherto fivcn themselves unnecessary trouble in endeavouring to apply to their systems the four graduated divi- ttons of JUogiciaas, as Classes, Orders, Genera, and Species, thiv doing in some measure violence to nature; I believe that some^ thing certain may be determined with roq>ea to the number of woch dqg^ees in the distribution of fossib according to their constituent principles; but, as thb is not the place to be more diffuse on this subject, I reserve it for another opportunity: yet, vrith respeet to classing in the subordinate parts, it is best V> retain what may have been already introduced;— ;'2dlj. Mi- neralogists arc too nndetermined, and too much at variance, in what they call species ; but if the word shall be here taken in s determinate aense, ipeda are in gjeoeral all fossils which diftr essentially fmm j>n€ another in the reUtions of their constituti* no ; and 0 jf^cUt, therefore, will be ail fossils which essentiaUy agreft Jn these relations: further, all ibgle pieces of a species »k iw^ fividiuU or s/>tamaiu, which we substitute for the species, ai k is impossible to collect ^together the whole species (because it /consists of all its individuals which occur either on or under the aptface of the Earth); lastly, aU fossils, by whldi me spedes papfi into another, and in which one «r the ^ofihcr -chsntftfCr i$ catii*^ . iHj different, are varufm.

Of Mmtralogy iu General* 1 1

Otherwise than by the word usual in the language in which the translation is made.

%. 12.

It has also been the practice to consider a fossil as sufficiently distinguished by describing its uses^ by noticing its constituent principles, or by class- ing it here or there according to certain reputed principal characters; and to this cause is to be ascribed the neglect of perfect and correct descrip- tions of fossils according to External Characters. This has been carried so far that scarcely any one fossil is to be found in an Oryctognostical work described in such a manner, that it might be im- mediately known and distinguished from others re- sembling it. Yet this is the most essential part of Oryctognosy, and I would rather have a fossil well described and ill classed, than well classed and ill described. Of this, however, I shall here take no farther notice, the External Characters of fossils being the peculiar subject of this small treatise; to the detailed exposition of which I shall proceed, after having appropriated a chapter to the consi- deration of the characters of fossils in general, and •f the pre-eminence of the External Characters.

%

A TREATISE

A TREATISE

THE EXTEltNAL CffJSJCTERS

*

Of

FOSSILS.

CHAP. I.

Cffi iA^ characters ofFesnls im grneralf and ^ iie prjg* eminence and utility qfthe external Characters^

§. 13.

X HE cbajracters of Fosuk are aU tbeir properties, by vh^i yre distinguish them from each other, and from other substances. They are as num^oua «a the dUffex^nt modes of observing, them ; and heyice we have external^ intemiily phj/sical^ and empirical .^cifaavacters* . .

f. 14.

Extermd ekaracters are those which we discover solely through the means of our senses, in the ag- gregation of Fossils: they are aho called Seniible Characters, ^ the use of our senses being sufficient for their discovery.

Internal characters are those which we derive from the analysis of the constitution ef Fossils;' and, being discovered by the aid of chemical ageoits,

they are also called chemical.

B Physical

2 . On tKe External Characters

Physical characters are those which we derive from peculiar phymod properties of Fossils, and which are observed in the relations that Fossils bear toward other sobstanoes.

Empiric^ charMciers are those which, in forming an opinion of a Fossil, are deduced from the place of its formation, and from the Fossils with which it occurs, which relations are sometimes founded on one of its properties. I have called these Empirical Characters^ in as much as they are principally used by those whose knowledge of Fossils extends not beyond that of practical experience.

§. 15, That these four kinds of characters may be very serviceable in the explication of Fossils is sufficiently obvious ; but the question is, which are frincipath/ and pecidiarly requisite for that purpose ? To deter- mine this inquiry, let us examine :

1. Which of them are present in every species

of Fossils, and m each iTidividual:

2. Which most certainly evince the essential dif-

ferences of Fossils: •

3. Which niay be most accurate^ kmxvn and

defined:

4. Which may be most speedily and easily discO'

vered; and

5. Which may be discovered y independently of the

analysis of Fossils. Accordingly, I shall now examine each of the four kinds, and it will then appear which is peculiarly related to Oryctognosy.

§• 16.

of FossUs in General. 3

§. 16. EXTERNAL CHARACTERS.

1. Are present in every species of Fossils ^ and in every individual; because they are derived from their aggregation,

2. Th^ certainly evince their essential diffe^ rences:^ for since the External Characters are de- rived from the aggregation of Fossils; and the aggregation is founded on the attraction of the smallest particles, or molecules, of a Fossil; and the different attractions of these molecules depend on their different constitution; it follows that as the constitution varies, the kind of aggregation will yary also: and that as the constitution is the foun« dation ot the essential differences of Fossils, the External Characters will also certainly evince them. Indeed we are taught the same by experience; for we find, that as the relative proportion of the constituent principles of any one species of Fossils varies, and thus approaches nearer to, or even passes into, another; even so do its External Cha-

B 2 racters

* The Extenial Characters have been considered by some Mine* raloguts as inadequate to the distinction and explication of the diflTcrent species of Fossils. This opinion, however, arde from their being, unacquainted with all the External Characters which it is possible to discover in a Fossil, and which fully appears by the examples they adduce. Dr. Vogel in his Practical Mineral System, speaks first of Muscovy-Olass and Spccular-G^sum, and then of Mica and Talc, as Fossils not to be distinguished from each other by means of External Characters. I shall, however, prove the contrary in the jth Chap, by the full description of these examples.

4 On the External Characters

racters also vary, and approach nearer to those of the other spepics. — The following may serve as ex^ an^plcs: —

1. Copper 'Pyrites f which, when passing into Grey-Copper-Ore, loses its lustre; the grain be- comes, much fin.er^ and its greenish-gold-yellow colour inclines a little to steel-grey. When passing into .White-Coppei'-Ore its weight and hardness are increased, the lustre is somewhat diminished, the .grain ..becomes rather finer, and its colour paler, .or inclines a little to whitish :— when passing into Martial-Pyrites, it becomes harder also, the lustre diminishes, and its yellow colour inclines to red- dish instead of greenish. — 2. Grcy-Copper-iyre^ when passing into ^ Grey-Silver-Ore, increases in weight, becomes softer, and more of a lead-grey-colour. — 3. Calcareous Spar^ when passing into Sparry-Iron- Orc, increases in weight, and becomes yellowish- grey. The^e Examples may be sufficient to ex- hibit the variation of characters in the Transiti- ons: and since it already occurs even in theie^ we may safely infer the certain variation of characters in the species themselves. In general, however, as similar * iri External Characters as many species appear to each other, it requires only an experi- ' ended* and attentive observer to discover their dis- . tinguishing characters, which are not always par- ' :ticularly striking'; hence it often happens, that a ^nechaiiic, from nicre practice, is much better able to di^iuguish the Fossils that come within his sphere

according

of Fossils in General, $

according to External Charactei;s^ than many a mineralogist. ' "

3. T/iey may be accuratelj/ known and defined^ because to know and define them, and to observe how numerous they are, and wherein they consist, vte need only examine the differences in the ag- gregation of Fossils; which may be easily accom- plished by mere attentive observation, particularly as in this respect much has been already done.

4. They vmy he easily and speedily discovered^ because they directly strike the senses, and tha^ aid of other substances is not necessary for jhcir discovery.

. 5. J hey may be discovered independently ^of the analysis of Fossils; because they are solely deriv- ed from the differences of their aggregation.

§. 17.

INTERNAL CHARACTERS, "

1. Are present in every species of Fossils^ but caimot be discovered in every individual^ because such individuals, or specimens, are oftentimes too small for chemical investigation.

2. They certainly evince the essential differences of Fossils, being immediate consequences of their : constitution.

3. They cannot be so accurately known, and de-' fined as the former j — a perfect knowledge of che- mistry being requisite — ^ science which itself is not yet complete,

4. They

. >

€ On the External Characters

4. They cannot be speedily and easily discovered ; because to discover them many substances and ex- periments are necessary, which often require a large apparatus.

5. They cannot be discovered independently of the analysis of Fossils ^ being derived from their analysis.

§. 18. pkvSICAL CHARACTERS.

1 . Are not present in every species of fossils ; pecu- liar properties having been observed in some few only.

2. They do not always evince the essential differences of Fossils ; essentially different Fossils possessing often the same property, as amber, and several

w

precious stones, which, when heated, have in com- mon that of attracting light bodies.

3. Neither can they be accurately known and de^ fined ; because, the knowledge of them is founded

on natural philosophy, even in which their nature is not fully known : besides many properties of bodies are still undiscovered, and can be only gra- dually brought to light by many, and variously repeated, experiments.

4. Th^ cannot be easily and speedily discovered ; because other substances, and experiments, are ne« cessary.

5. They may be discovered independently of the analysis of Fossils ; because, we need only observe the relation which an individual bears to another substance^ with respect to a particular property.

iyf Fossils in General. 1

§. 19. EMPIRICAI. CHARACTERS.

1. Are not present in evety species, and even where the;/ are, not in all their indhiduals : for in respect to the former, many species of Fossils are found nearly in all places, and in conjunction with all others ; and with regard to the latter, individuals

'sooietimes occur, with whose place of formation we are unacquainted, and which are wholly unmixed with others.

2. They do not always evince the essential differ^ ences of Fossils ; being too general, and appertain* ing most commonly to a whole genus, or at least

' to the greater part of its species.

3. Neither can they be accurately known and de* Jfw^rf ;. because 1st, the nature of these properties

themselves is as yet unknown ; and 2dly, their de- termination depends entirely on Experience which can^be only gradually acquired, and scarcely other- wise than on the spot where they are produced.

4. They can be easily and speedily discovered : and

5. Independently of the Analysis of Fossils ; be- cause we need only observe what accompanies an individual, or what is mixed with it.

From the foregoing consideration it follows, that empirical characters are altogether imperfect : — that physical characters are also imperfect, and the dis- covery of them inconvenient : that internal, or

chemcid

I

8 On the External Characters

chemical characters are tolerably complete and cer- tain, yet somewhat indeterminate, and the discovery of them attended with the greatest inconveniencen^ an able chemist being alone equal to the task ; and besides, that many substances and a large apparatus . are requisite^ each individual, which shall be known' solely by means of these characters, ix^ust be ana-« . lysed, for which many are unfit, and others to*« small : lastly, that External Characters are thoroughly complete, certainly discriminative, most generally known, easily defined, and conveniently discovered, and hence principally and peculiarly related to oryctognosy.^

§. 21.

The utility of the External Characters, therefore, applies chiefly to the Mineralogist who forms from them his External coDceptions of fossils, by means of which he distinguishes and describes' each species, and even where thousands 'of individuals occur to- gether, and no other means of examining them are presented than those afforded by the senses, is yet enabled to ascribe each to its appropriate species. They are very useful, and even indispensable to the chemist ; who, if unacqudinted with them, could place no reliance on his examinations of Fossils : fot

how

* Of the three other kinds of characters, the Chemkal appertain peculiarly to Mimeralogical Cbimistry^ which treats of the Analysis of Fossils ; — ^the Physical to Natural PbiUsopby ; and the Empirical partly to Mineralogical Geography^ and partly to Geognosy, In the 5th chap.

1 shall further notice them, as far as fome may be apjilied to tkc explication of Fossils,

of Fossils in General, 9

bow is he assured that the individual, ivhich lies before him, is actually of that species of Fossils it IP his intention to examine, if he does not already poss^, by External Characters, the correct con- ception of its Exterior ? Several instances might be adduced which render it very, probable, that phae- flomena noticed- by chemists in the analysis of one or the other Fossil have been occasioned by a diffe- rent Fossil, and which they confoundcid with this, or at least by others with which it was mixed : and whence could this have arisen, otherwise than that the Chemists did not know how to distinguish their subjects oryctognostically, i. e. according to External' Characters ; lastly, a knowledge of the External Cha^ racters of Fossils is productive of no small advantage to the Miner y enabling him to form an immediate opinion of every fresh appearance or discovery in the Mine, which he has rarely an oportunity of examining chemically ; and indeed it would sometimes be at^ tended with too many incpnveniencies and diflSi- culdes* In the separating and dressing of Ores, he can have no other mode of distinguishing them than by External Characters ; which advantage is en- joyed by every one employed in the mechanical working of Fossils.

CHAP*

CHAP. II.

History of the External Characters of FossQs,

T

§. 22.

HE most ancient writers on mineralogy, «• Theophrastus,* Flint/ j J and others, described Fo»< sils merely with regard to their use : — hence it arose, that they made little mention of their External Characters, and only occasionally employed^ one^ cir the other, a& an assistant in their descriptions.

§. 23.

For many centuries after their time, we had not any professed writer on Mineralogy, and the Science itself had become aIaK)st wholly extinct : — it is, therefore, easy to suppose that nothing remarkable has appeared respecting the External Characters of Fossils.

§.24.

At length George Jgricola arose, the father of Metallurgic Science, and produced among other valuable works his treatise de natura/ossilium.lli — In this he is the first who has introduced the proper

use

* Theophrasti Iresii m^} rSv x£&Mr fflBiuof. i Caii Plinii Sccundi Historia Mundi, Lib. XXXVIL I Ccorgiiu Agricola de natura fossilium, Basilez 1546, foL— I paM hf preceding mineralogtcal writers, at Avitenma^ Alhetiut MagmtSf llftn 9M their works do not contain any thing worthy of note respecting Sztcmal Characters.

External Characters of Fossils. 1 1

use of External Characters as applied to the dis- tinction and description of Fossils ; for which pur- pose he has also in the beginning of the first book drawn up a system of External Characters, and fur- nisbed the following notices;

1. Th^ Appearance,

the colour color ^

the transparency facilitas translucida,

the resplendence /ulgor^

the lustre nitor^

2. The Taste,

3. The Smell,

4. The Touch,

the cold and warmth frigus et calor^

the moisture and dryness humor et siccitas,

the greasiness and meagre- ^ pinguitudo et ma^

ness ^ critudo,

the compactness and porosity spissitudo et rantaSp

the hardness and softness durities et meUitudo^

the roughness and smoothness asperitas et lavor^

the weight and lightness gravztas et levitas.

But besides these, he reckons the following among the particular properties of Fossils, by virtue of . 'which they are either passive or active :

the viscidity. tentovj

the flexibility flexibilitaSy

the friability and fragility friabiliias etfragUitas^

the

13 History of the

the thickness and thinness crassities et tenuitaSf the ductility tractabilitas,

cleaving fissio^

the iissures Jissa.

Quite at the latter end he also particularly noticed the shape and size of Fossils :

The Form,

1. Indeterminate^

2. Tabular, 8. Bound f

perfectly globular figura glohi absolutif

compressed globular /. globi compressi^

Semi-globular	f. globi dimidiatif
cylindrical	f. cylindrical
conical	f. metiSy
turbinated	f. turbinis.
J	4. Angular r
triangular	Jigura triangula^
quadrangular	f. quadrata^
pentangular	f. quinque angulis^
hexangular	f. sexangulaj
polyangular	f. pluribus angtUis
acuminated	cum mucrone»
5. Resembling other bodies :
horns	f. comun
the moon	f. luna^
hairs	f. capillorumy
iii6 ears	/. aurtcularum.

cells

External Characters of Fossils, 13

cells /. favarum,

lentils /, lentiumy

the trunk of a tree f. arboris trunci simtlis^

darts /. sagitt^j

acorns , f. glandis.

6. Appears in the fracture or internally.

7. Marked with lines, and resembling

eyes /. oculif

stars /. stellarum,

fishes f piscium,

animals f animaliumy

representing moun- ) ^ . „.

, „. I /. montium et convalhum* tains and Tallies )

bushes f nemprumj

rivers /. fluminum.

The Magnitude,

Of each of these characters he has mentioned the differences, and added examples of Fossils by ivay of illustration. Although Agricola has done as much in this system as could be possibly expect- ed from him at that time, it is, nevertheless, (be- ing the first attempt of the kind,) very imperfect: many Elxternal Characters are wanting, and seve- ral noticed which are not properly characters. Besides, they are neither arranged in a good order, nor defined by explanations. His descrip* tiona of Fossils are also very incomplete.

§. 25.

14 History of the

§. 25.

After Agricolay two centuries elapsed in which nothing particular occurred with respect to Exter- nal Characters, except that they were applied by some mineralogists to the classification of Fossils^ and particularly of Earths and Stones. It so hap- pened that these Mineralogists were also Botanists and Zoologists^ and therefore wished to introduce into mineralogy the methods of Botany and 2k>o- logy. Among these Gesner* and Scheuchzerf may be particularly noticed. They have had many followers in succeeding^ and even in the present times.

§. 26.

When at length in our times, Mineralogy in ge- neraly and Oryctognosy in particular, began to flourish, among the many publications that appear- ed on this science, there were several which treat- ed either partially or wholly of the External Cba- ractra's of Fossils. The first particular Treatise on this subject was produced by professor Hausen, in the year 1737 ; X but as the author had solely the da8sifi<!atioit of Fossils in view, the greater part of the characters are .only noticed in an inciden- tal

• Conr. Gesnerus de figoris lapidam. — Hguri 1565-4.

t Joh. Jac Scheuchzcr, Mcteorologia et oryctographia Hchre^ lica- — ^Tiguri 1 718-4.

t Chr. Aug. Hauseoii Prog, ad tolcnnia promodoiu— Mag^ Lipsis z 737-4*

•

External Characters of Fossils. 15

tat manner, and merely the lustre, the structure^ and the parts into which Fossils divide in breaking are considered in detail, as being adapted to his purpose. It appears to fne, however, that the distinctions of the author are oftentimes not suffi- ciently discriminative, and at other times too suIk* tae.

§. 27.

WalUrius was the first who, in his Mineral- riket/^ published the year 1747, gave more com- plete descriptions of Fossils according to External Characters, than any that had been received to that time ; hence amidst the number of Mineralo* gists who succeeded him, some are to be met with (among whom Cartheuserf and BomareX deserve particular notice), whose descriptions are still more complete, and since their time Oryctognostical books in general are, in this respect, considerably distinguished from the precedinjg. But we may still object to the descriptions, both of the former and of the latter: 1st. that they are incomplete; characters being wanting that actually appertain to them: 2dly. that they are not sufficiently distinct and defined; neither of these Mineralogists having previously arranged the External Characters, which he employs, in a system, which would then have

been

^Joan Gottsch. WaUerii Mineral-rickeL— -Holm 1747-8.

t Frid. Aug. Cartheuteri Elementa Mineralogis, F^f. ad Viadn

* fVaSmoDt de Bomarc, Minenaogie. ^ BvU x76a-8.

16 Iftstory of the

been his constant guide in his descriptions; nor having previously defined and explained them, so that it might be known what was understood by this or that character : 3dly. and lastly, that each of them, in order to express one or the other character, has appropriated to the same a different^ nay sometimes more than one different denomina- tion.

The second work, that treats in particular of this subject, proceeded from Dr, Gehler in the year 1757, being a dissertation de characterifms FossU Hum extemis. The author has classed them after the five senses, and gives the following notices:

1. The Smell,

arising spontaneously sponte enascens, arising from attrition! attritu s. defiagrando enas-- or combustion 3

2. The Hearing,

the crackling crepitusy

the ringing sonus quern edunt percussi^

3- The Taste,

4. The Touch,

smooth and rough litve et asperumf

ft

greasy and meagre ptngue et macruntf friable and solid friabik et densuw,

. light and beavy leve at grceve.

5* Th6

cens,

External Characters tf Fossils. IT

5. The Sight,

the colour color,

the size magnitude,

the specific gravity gravitas specifica,

the ductility & fragility ductilitas et fragUUas^

the transnarency and ) „ . . .

'' > peUucidttas et opacitas^ opacity 3

the hardness durities,

the external shape figura seu forma.

§. 29. Hitherto Agricola has been followed by Lin^ fueus alone, who, in the last much improved edi« tion of his Systema Natural, has at the begin- ning of his Mineralogy, which forms the third part of his system, considered and defined most of those characters, of which he afterwards makes use in the description of Fossils.

But the order, if such it may be called, in which they are arranged, is not to be applauded; and in the next place, they are not comfrfetet many being deficient: besides most of the expli^ Mtions of the characters are too concise, and con- sequently obscure and unintelligible ; and lastly, illustrations by examples, which are so serviceable in rendering the explications clear and intelligible, are wanting. Those External Characters, which Linnseos considers in his Mineralogy under the ar- ticle of Words of Arty are the following : —

c 1. The

* CaroUa Liiui6 Syetema uituraB, HolmiXy 1768, Sro. Tom. nt. • S9 tc 30.

28

History of the

I. The external form.

of an indeterminate form amorphum^
crystalline		crystaUinumf
cubical		tesselatumi
prismaticdl		prisma, s. columnaf
pyramidal		pyramis.
lenticular		Icntiformej
nodular		nodzUosumf
kidney form		rcniformej
even		planum.
4	2.	The Coating,
shelly		cmstosunif
cortical		corticosumj
concentric		concentricum,
kernelly		embryo.
	3.	The Surface,
superficial		superficiale^
rough		scabrum.
smooth		lave.
shining		•-' mtidumf
glimmering		micans.
	4.	The Particles,
compact		compactum.
impalpable		impalpabile.
dusty		puhendentum.
arenaceous		arenosum.
granular		granulaium,

S. The

External Characters iff Fossils.

19

5. The Fibres,

fidres resembling ears of Com

interlaced fibrous

parallel fibrous

scaly

acerosuiUp

decussatum, Jibrosum, squamosum 9

6. The Structure,

foliated memhranaceum^

fissile fissiUy

diverging from the centre concentratum,

consisting of fragments fragmentis,

!• The Hardness,

striking fire

(capable of being scraped

firm

fragile

sectile

friable

brittle

flexible

malleable

staining

staining and marking

giving a streak

giving a white streak a red streak a black streak

scintillansy

rasilcy

durum^

fragOtj

sectile,

friabikj

rigidumi

flexile^

fnalleabile,

inquinansy ,

inqtiinam scriptura,

inquinans tritura,

tritura alba,

tritura iiibra,

tritura nigra ^

2 8. The

V . ..?;

M

Hisicnry of ike

t. Thfe Colour,

opaqtre

scmi-transparenC transparent colourless

coloured

•

reflects the rays refracts <jie rays

OpdCUTUlf

diaphammif

peUticidumy

hyalinumf

tinctum,

reflexioy

refractioy

Linnaus has acquired no small degree of repdk tation by his exact determination of the Crystal- lizations of Fossils, nearly all of which, before hitf time, if not as ob^rioaB as the Cube, were called polyedral ; it were only to be wished that succeed- ing Mineralogists bad taken the proper adrantage of the pains bestowed on this subject.* The Author treats of the Crystallizations in particular at the end of his Mineralogy, and determines them in a three-fold manner: 1. by giving the number and form of the sides of a Crystal : 2. by bringing all Crystals under two principal genera, one of which be calls prismatical (columnar), namely those whose form extends in length ; the other cubical (tesseras), namely those whose form is generally of equal length, byeadtb> and thickness, and consequently

presents

* It is but justice to remark that w^en this was written, Mr. Werner was unacquaiated with the ingenious and deborate Crys* taUographie of Rome de risle, of which the first edttion appeanJ

lit X77». TRAKSLATOIU

External Characters ^ Fossils* -21

9

presents nearly a globular appearance : 3. by en- deavouring to compare all Crystals with the Crystals cf Salts, mnd accordingly as thty %gree with one or tl» other, apprttpriatiDg to them the same name* The Author meotioiia fire kinds of known Salts^ under which, on account of their coincidence in figure, he arranges most of the CyrstalUzaiions of the Mineral Kingdom; these 9xe Natron, Nitre, Ahmij C&mrnon Sali^ and Vitriol; those Crystals 'which cannot be brought under any of thege 8»lts» the Author suf^^oses to appertain to, and to hava received their form from a peculiar kind of Salt us yet unknown^* Though k is so far useful to compare the Crystals of Fossils with those of known Salts, as thereby the description of the former i» rendered more clear and intelligible; I nevertheless entertain niany doubts of the truth of the position — ^that the Salt which coincides in figure with a crystallized Fossil,' shall also be ih% cause of the figure of this Crystallisation.

With respect to the descriptions of Fossils, ac« cordiiig to External Characters, I find it here also necessary to observe what I have already said of pU others, that they svre still very incomplete*

§^ 30. Peithner

» fc » lAm» MmmUte* AetdoB^CM. YoL L dimrt. de Gryv filinniin gpicnikm Eciyoad. Uartiao Ka/sbkr, Holm, i; jo-^

22 * ffisiory of ihe

§. 30.

Feithner^ an<f SiUf are tiie first, who, in their systems of. Mineralogy, have attempted a Tabular Arrangement of those External Characters, by which they would communicate the External con- ception of a Fossil.

For this purpose Peithner employs seven co^ himns, of which,* however, the one or the. other, when superfluous, is omitted in several of the Tables; the first of these columns contains the colour^ the second the transparency^ the third the form, the fourth the taste, the fifth the smell, the sixth the weight, the seventh internal properties and effects, discovered by different experiments j in which latter are also fre(iuently placed several External Characters, which cannot be brought imder the preceding, as the hardness, the solidity, the streak, the stain, and others. Before these columns the author places the names of the varie- ties to be described, and which are already arrang- ed in a system, following each other in a natural order; in the columns themselves are placed, in a line with the name of the Fossil and under the abovementioned heads, those External Character^ ^hich are to constitute its External conception.

But

*Joli. Thad. Peithner*«, crste Grunde der BergwerkKwrnen- ichaftcD, zwote abhaadlim^ ^bcr die KGneralogie, Prag. 17704^

f J. Hill. Fossils arranged accordiflg to their obvioui clu^ cactcri. Londoiii 1771-8.

External Characters of Fossils. 23

But here I must observe, that the Exteroal Cha- racterS) employed by Peithner for the determina- tion of Fossils, are oot sufficient to impart com- plete External conceptions of them ; that these External Characters should have been previously explained, in order clearly to ascertain the idea which the author attaches to each; that the or^ der in which they are arranged is not the best; and lastly, that under one head, instead of the proper character, another is very often placed, which does not at all belong to it, as e. g. under transparency-^the lustre; under form — the struc- ture.

In HilCs Mineralogy, the External Qharacters are arranged in six c^ltmins, of which the first contains the form^ the second the hardness^ the third the weighty the fourth the surface^ the fifth the colour^ the sixth particular properties; in which latter also are usually placed, the transpa^ remyj the smelly the tasie^ or some other Exter- nal Character ' which could not be brought under the foregoing heads: and those External Charac- ters which are to convey the External conception of a species of Fossils, are always placed in the columns in a line with each other, and above is the name of the species. The author, however, employs too few External Characters to impart perfect External conceptions of Fossils; besides, they are too indeterminate, and very ill arranged: characters are also frequently placed under one

bead

f^ Htstcry of i%c

liea4 which do not beloog to it, and sonetimei such as are no characters at all— e. g. who would consider on inspecting a whole coHectioD^ or even • single specimen, whether the species constituted jsntire mountains, or occurred in beds or layers; and yet this the author {daces under the head of the External Form.

However, this method, if brought to perfection^ would not be without its use^ for in the External descriptions of Fossils, ii would fXNMtantly dfarect us to the observance of one and the tame order f and in the •descriptions themselves the determina* tion of the External Characters might be rendered much more concise. This object has been attam-> cd by both these authors, and they are, therefore, to be preferred to all those who have preceded, or followed them. On the other hand, however^ several inconveniences occur ; the Tables, if made Biore complete, and consequently more extensive, would require a much larger, nay too large a form, and frequently, where a more copious ex* pression would be necessary, it could not take place ; whereas it is my settled opinion, that with re- gard to descriptions, it is much better to be dif* fuse in , expression, than, for the pake of brevity, to prove obscure and unintelligible*

§. 31. ^

Very recently Wallcrius*, (of whom we have already had occasion to make honourable mention,)

has * Joh. Ctottftcb. Wallcrii STitcma Miacralo^cum, Holaisi X77vli

Ej(temal Characters of Fossils. 85

hu produced his Systema Miner^logicum, which \re may pronounce to be the most complete that has hitherto appeared, not only as to Mineralogy in general, but particularly in the description^^ Fossils according to External Characters. I must, nevertheless, still observe, that in his External Des« criptions External Characters are frequently want-- ing, and that the External Charactecs contained in the descriptions are neither ivell arranged, nor sufficiently defined*

\'

CHAPV

CHAP. lU.

Of the Definition of the External Characters of

Fossils,

§. 32.

w,

HAT External Characters are, and how many other kinds there are, has been already mentioned in the 1st Chapter. It was there £^lso shewn that^ with respect to the' purposes of describing and distinguishing Fossils, the External Characters are preferable to the other, and hence are those which peculiarly appertain to Oryctognosy. But to ap- ply them to the description of Fossils, and to the External, or Oryctognosticat knowledge of them to be derived from the descriptions, necessarily requires — that they be defined as accurately as pos^ sible.

§. 33.

For how can a student in Oryctognosy obtain correct External conceptions of Fossils from their descriptions, if unacquainted with the true mean- ing of the different External Characters which are the foundation of those descriptions ? This indefi* nitcness is still increased when Oryctognosticat writers bestow different denominations on the same character, so that two different persons frequently

form

External Characters of Fossils, 27

form very different conceptioDs of the same deno- ^ Biioation ; nay, sometimes a Mineralogist applies cvep several denominations to the same character, and one denomination to different characters. This indefinite application of the External Characters is a principal cause of their imperfection, and of the consequent inutility of the descriptions of Fossils: on the contrary, the descriptions ^vould have at* tained perfection had the External Characters beea as well defined as they are arranged and complete. In Mathematics the method of teaching owes great part of its perfection to the definition of terms; for here all combine the same ideas with a sum, a line, or an angle, and again all apply the same denomination to one idea. If then Minera- logists would unite, with a view to render Oryc- tognosy, in this respect, ^s nearly- similar as possi* ble to Mathematics, what advantages ipight not ibi^ science derive from their endeavours?

§. 34,

The definition of the External Characters of Fossils in general, requires, 1st. that we know what External Characters are ; 2d. how many their number; 3d. that we apply to each an appropriate and determinate denomination; 4th. that we give of each the proper and adequate conception ; and 5th. that we endeavour to shew the relations in T^hich they stand to each other.

What

99 Of the DefiniHon of the

§. 35.

What External Characters of Fossils are^ may * be found in the commencement of the 1st. Cllap« ter of this Treatise. The conception which was there given of them will enable us, io every des« cription of a Fossil according to External Cha- racters, to omit, and divest it (in order to ren^ der it the more clear) of whatever does not belong

to it.

§. 36.

The number of External Characters may be learned, 1st. by collecting all those which have hitherto been made known and employed by Oryc- tognostical Writers; and 2d. by discovering in the Fossils themselves those which remain, by diligent comparisons. In the system contained in the an< nexed Tables, and which I shall follow in the course of their explication, I have endeavoured to determine their number as precisely as possi- ble. It is on this accuracy in the determination pf their number that the completeness of the Ex- ternal descriptions of Fossils, or of their External f:onceptions, depends; for if a correct External conception of a Fossi^ shall include every diffe- rence^ perceptible in the Fossil by the senses (and these are its External Characters,) the conception will be incomplete if it do not include all the differences which distinguish this Fossil from others^

«

9r may distinguish it froni Fossils perhaps as yet unknown : but how can a Mineralogist be assured^

that

External Characters of Fossils. 29

tbat the External conception of a Fossil, convey- ed by him through its description, includes all its External Characters, if unacquainted with the num« ber which it is possible to discover in a Fossil? As on the eae hand, the conception of what Ex- ternal Characters are, ensures to us the c^tainty > «f ilot saying too much in descriptions founded upon them, so on the other hand, die knowledge •f the number of External Characters will obviate the poMibility of sajing too little.

§. 37.

•

iTht denomination of a character is appropriate ii k fuUy express its quality, and that which dis« tinguishes ii from others of its qpecies or genus ^ wad determinate, if it be the wly pne appUed to tme cbarftcter. It is. the more necessary to be particular in the chbice of the former, as it is in some measure the foundation of the latter. Where die denomination is m^ely optional, it will be, ittfficieDi to adopt those which have been in most coamon use with eminent Mineralogists* I also^ find it necessary to observe, that the denomination should always be written according to the best idiom of the language* These are the rules which 2 shall myself follow in giving denominations to characters; I shall not fail, however, to notice in their proper places such as are defective or syno* nimous. The advantages which result from appro* priate and determinate denominations, and the un- certainty

50 0/ the Definition of the

certainty and confusion which proceed from the contrary, have already been sufficiently shewn in §• 33.

§. 38.

The adequate conception of an External Character may be conveyed by a correct and clear explication. But, as full and proper explications of the External Characters are attended with some difficulty, their conceptions being frequently intimately connected with each other, it is useful to analyse the complex characters, in order to render the conceptions of them as simple as possible, and then to explain the conceptions of the simple, characters onlj'. Com- plex External Characters are such as consist of two or more simple characters, as e. g. scorious ; here the conception of a conchoidal fracture is united with that of lustre ; specular — here the conception of a strong lustre is combined with that of an even surface ; vitreous — when the conception of lustre is connected with those of transparency and a splintery fracture : and as all the simple characters, of which these complex consist, are in their own nature transitory or passing into others^ as e. g. lustre which passes into dullness ; splintery into even ; and this again into conchoidal ; this difficulty must be considerably increased when many such simple characters are complicated in one.* In respect to the perspicuity of the explications themselves, they

may

* The proper course to be punued in descnptioas with complex character! will be pointed out in the 5th Chapter.

External Characters of Fossils. 3 1

■lay be considerably assisted by well selected illus^ trative examples. Well selected examples are those in which the character to be illustrated does not pass into another nearly allied to it, as in^the firous where it passes into the striated or into ther compact; but rather, in which it is best and most clearly to be perceived. We should also in these explications cautiously ayoid employing brevity at tbeexpence of perspicuity.

Id the explications of the External Characters which are contained in systematic order in ther following Chapter I shall, as faf as possible,, ex-^ hibit no other than simple characters ; (such, how-> ever, as are complexy I shall notice in their proper places;) and in every explicatioD, I shall, if prac« ticable, adduce at least 3 fossils as illustrative ex> amples of the character to be explained.

The advantages which good explications, ac« companied by illustrative examples, afford to the definition of the External Characters, and to the consequent intelligibility and utility of the de- scriptions of fossils founded on these characters, have already been sufficiently shewn, and are in themselves so obvious, that to make any further comment would be unnecessary.

§. 39. '

The relations in which External Characters stand to each other may be best made known by classing them in a coiPrect system, i. e. by distributing them

into

32 Of the Definitum ef ike

into their Genera and Species, and arranging these according to their natural order. Bat Genera of External Characters, or gtneric characters y are those which direct us to what is to be determmed in a fossil, such are Ccdour, Cohesion of the particle^ Weight, Taste, &c. Thus in saying Copper* Pyrites has a colour, I have not determined any thing, bat merely pointed out what is to be de- termined. Again Generic Characters are comrmti and particular ; common arsr those which point xmt what is to be determined in every fossil, and par- tiadoTj what is to be determined in oTie hramh qf fossUs only; of the former, those adduced above may serve as an example; of the latter, we may notice solidity^ sound, &c. which are solely appli* o^Ie to one branch of fossils, viz. the solid.' Specie^ of External Characters, or specific characters, are those which determine what may be said of a fossil with respect to a generic character; as e. g., ii» saying that Copper^Pyrites, with respect to ita colour, is yellow ; or, with respect to its hardness, is halfJiard. It ia from these specific characters that we form the External conoeption of a fos|piI» and that we frame its External description ; whereia the generic characters serve merely to class tbs apeciiic under Genera in the System, and to indi- cate those for which we are to seek ; lastly, varieties are those by which a fossil is accurately determined with respect to a specific character, as e. g. in say* log that Copper-Pyrites is brass-yellow, or that the

Diamond,

External Characters of Fossils. 33

IMamond, in respsct to hardness, is extrerneh/ hard : for, since specific characters have often several varieties, and fossils are frequently distinguished merely by one variety, it becomes necessary, in . order to determine 'a fossil with respect to one or the other generic char^^cter, not only to mention the specific character, but also the variety.

Ad arrangement of all these External Characters according to a natural order necessarily requires a previous determination of the natural order ; as however the External Characters of fossils are aU those diSerences or distinctions which we perceive in them by means of our senses, their most iiatural order will of course be that in which these dis- tinctions present themselves to our senses, and become subject to observation. This is the principle according to which all generic characters should be arranged. But, to determine the order of the specific characters and their varieties ; accordingly as they belong to this or that generic character (as they cannot be* arranged according to the above inentioned principle, because of those which belong to one Genus there is never more than one found as a difference of this Genus)-«-we must seek some other principle ; and this will not be difficicult to discover, if we consider their nature : For as all specific characters are merely the differences or vari* eties of a generic character, that order will surely be the most natural in which the generic character varies, and in which they pass one into the other.-—

D This

34 . Of the DefiniHm •/ Hu

This .abo holds good with respect to the wmeties of the speoific cbarocten.

In 9 system y therefore, of the Extenud Characters of fossils, all the varieties will be arranged under their species, the corresponding species under their commoo, or particular genera, and the particular genera under the one or the other common genus to which they belong ; secondly^ all genera or gene- tic characters will follow each other in the order in which diey present themselves to our senses ; so that those which the Eye observes stand first : for we much sooner see a fossil than examine it by the touch, or any other sense. Among these again, the colour will occupy the foremost rank, as we much sooner perceive and distinguish the colour than the external form, &c. In conformity to this principle, after those which strike the eye those will follow which are observed by the Touch*; and ' lastly those which belong to the Smell or the Taste. Thirdl^j all specific characters and varieties will follow in the order of their transitions, or in which they pass one into the other ; as e. g. in the frac- ture— ^to the fibrous will succeed the striated^ the foliated, the slaty, and then the compact. It is in conformity with these principles that I have com- posed my system of External Characters, contained in the annexed tables.

The advantage of such a system is^ in general, to make us better acquainted with the nature of External Characters^ and to render them intelligible;

and

External Characters of Fossils. 35

and in particular, to serve as a guide in forming External cbnceptions of Fossils, and in framing de- scriptions founded upon them, by which the dis- corery of the External Characters is not only fa- cilitated, and the possibility of omitting any .6ne prevented, but also in the description itself the one often elucidates the other, and greatly assists in re- taining the conceptions.

§.40.

As I believe my readers have been sufficiently informed what External Characters are ; in what manner they should be explained ; and wh^i^in the deficiency in this respect has hitherto consisted ; I shall now proceed to the explication of each io particular.

CHA?^

CHAP. IV.

Explitation of the External Characters of Fossils,

I. The Colour.

§. 41.

Ai

.MONG the common generic characters of. Fossils, the" Colour is the Jirst which strikes the senses. It is also one of the most certain cha- racters: for among others it serves as the princi- pal distinguishing mark of most Ores, Inflamma- ble Substances, and Salts. Who knows not how easily Native-Gold, Native-Silver, Vitreous and Corneous-Silver-Ores, Copper-Pyrites, Vitreous- Copper-Ore, Specular-Iron-Ore, Sparry-Iron-Ore, Galena, Tin-Stone, Sulphurated-Bismuth, Striated Red-Cobalt-Ore, Arsenical and Martial-Pyrites, Natural Sulphur, Pit-Coal, Mineral-Pitch, Alumi- nous-Shale, &c« are distinguished by the Colour? besides many others whose names are derived from it, as Red-Silver-Ore, Red, Green, and White- Lead-Ores, Brown-Iron-Stone, Blue-Martial-Earth, Red-Antimonial-Ore, Yellow-Blende, Grey-Cobalt- Ore, &c. Now, although the Colour is less to be

depended

External Characters of Fossils. 37

depended iipon, in Earths and Stones'^; it never- theless renders a great part of them distinguisha- ble : for, various species of Silex are distinguish- ed by it^ as also of the muriatic Genus, which are in ji great measure distinguished by their green, or greenish- white Colour ; and likewise Swine-stone by its brown Colour, which is a tran- sition from light to dark-brown, not to mention many others.

Those Mineralogists therefore err who consider- the Colour as an uncertain distinctive character of Fossils ; it is true that alone it is not sufficient to distinguish Fossik from each other, but this also holds good with every External Character, and it is the totality only of all the possible External Characters of a Fossil that constitutes the distinc.. tive conception of its Exterior.

§. 42.

According to the exact conception of Natural Philosophers, the Colour is that property of a Fos- sil,

*The reason that Colours La Earths and Stones are some- tunes so Tariable, is— that their prixnitive Colour is properly white, as of Inflammables it is black, and of Metala Vari^t- cd| and as white is that Colour which, by reason of iu clear- ness, is most easily and evidently changed by a trivial admix- ture of a substance of another Colour; it happens, that when- ever only a small portion of inflammable or metallic particles enters into the constitution of £artl|s or Stones, their Colours are directly changed to brown, red, yellow, green, blue, &c.~r Whereas Metals, on the contrary, scarcely become lighter from a slight admixture of Earth* or darker from a small portion of inflammable matter.

M ExplicaHon ^ the

ail, as of every other substance, which by the power of the figure, or association, of its Mole-* cules, causes a different refraction of the incident rays of light, and hence produces a different sen- sation in the eye.

The Colours which are observed in substances in common life have been distinguished into certain principal colours ; all those which are in ^some de* gree connected with each other having been brought iinder one Genus, and the generic name of the princ^>aI colour having for the greater part been added to the distinctii>e name of the species, as. e. g. gold-yellow, grass-green, brownish-red. To know, therefore, the number of the principal co- lours, and to which each colour belongs, we need only attend to the difierent generic names of co- lours. There are ^A/ principal colours, and these, are whiie, grey^ black, blue, green, yellow, red, and brown.*

§. 43.

* I could not here enter into an adoption of the seven Co* lourt into which the Solar ray is divided by the Prism as principal Colours, nor into a distinction of the Colours accord- ingly as they are either simple or compound ; nor could I omit white and black, the former being considered as a combination of all colours, and the latter as the mere privation of light or colour: for these are distinctions which pertain to the Theory of Colours among Natural Philosophers, and cannot be weU applied in common life, in which black is ranked among the Colours as well as white and yellow; and green, which is mix- ed, considered as a principal colour, as weU as red which is simple.

In the adoption of the principal Colours enumerated above 1 am countenanced by Dr. Sdueffcfy who has exhibited tbeai^

with

External Characters of Fpsiils. V

§. 43.

The Colours which are subordinate to these eight principal colours vary much from each other accordingly as they are intermixed.

Id order, therefore, to define these difierent ▼»- riettes of the principal Cdours, we must give to each a determinate and systematic denomination, arrange it accordingly as it passes into others Jn relation to its composition, then determine the composition itself, and lastly corroborate and elu- cidate the explication by appropriate examples of bodies drawn in general from nature and common life, and in particular from the Mineral kingdom. Among other natural bodies, flowers which possess Jixed Colours serve as distinguished examples.*

§. 44.

with the exception of the ffrtjt in hit sketch of a general atM-> datioa of Goloiin, Regenspurg 1769 4. I am, however, joftilied in' adding the grej colour by obienring, that it occun vtrj fire- qncntlj in the Mineral Kingdom ; that the attempt to bring it nnder any one of the other Oolonn would be attended with many difficulties, and that, if we have respect to denominafionf» 1^ it is considered in common life as actually differing from the

others. Moreover the plan proposed by Dr. SchxSkr in the same work u good ; and were it already executed and. exfmdfd to the Mineral Kingdom would now come very seasonably to my assistance.

At some future time I may, perhaps, take the trouble to compose Maps of Colours, according to the proposed plan, for the purpose of illustrating the Colours of F6ssils.

* It is here necessary to observe^ that the Colours of many Fossils occur impure or cloudy, and of others as transitionSff or as stronger or weaker approachet to other colours, and there- §otc are not actnally the esact coloms here adopted and do- lisminatcd.

4B Explication vf the

§. 44.

A denomination is systematic when it not only distinguishes the subject from other species^ but also expresses the genus to which it appertains, and thus unites the generic name to that of the species, as, e. g. blueish-black, scarlet-red, sky- blue.

The generic names of Colours are determinate; for these are the names of the principal Colours. But the specific denominations, or the names of the species, are selected variously : sometimes they are borrowed from substances in common life, as e. g. milk-white, sky-blue, canary-green, liver- brown 'f to which also those derived from the metals belong, as e. g. silver-white, steel-grey, gold-yellow ; sometimes they are taken from a pointing Colour produced either singly, or. by mixture with others, as e. g. indigo-bloe, azure- blue, verdigris-grecn ; and sometimes they are de-r rived from the principal colour, on which the colour to be denominated verges by an admixture with it, as e. g. blueish-grey, yellowish-brown : it is very rarely that the name of a person is chosen, as e. g. Isubella-yeliow.*

With

*A8 it 18 rather uncommon, it would appear very singular to deriye the denominations of new species of colours from per- sons; and to apply numbers to that purpofe, as proposed by 'Dr. Schxfier, would not be sufficiently striking, independently of the difficulty of retaining them in the memory. I conceive the best mode to be that already mentioned) vi&: to borrow

the

External Characters bf Fossils. nh

With respect to the denominatioiv of colours, I shall only farther remark — that those derived from Metals are solely applied to fossils possessing a uietallic appearance.

§. 45.

The composition of these varieties of colours is determined by shewing what colours constitute the composition, and the relation in which these colours stand to each other with respect to intensitj/ : the latter may be accomplished by means of a few de- terminate expressions employed in pointing out the colours which occur in the composition. These are — that the colour which predominates in the composition, and in consideration of which the mixed colour has been brought under one or the other principal colour^ is, as the generic denomi- nation, placed last ; and that which has principally altered it is, as the denomination of the species^ prefixed to it with the relative termination ish, at e. g. blueish-black, reddish-yellow, brownish-red : if, however, the* latter be but slightly mixed with the former ; or that besides the two usual colours, a third enter into the composition in a slight degree, the expression inclining to is employed : or if i(

shall

the dauMninadon cither ftxMn a subject in common life, to which the colour pccnliarly and properly belougt, and which, if the subject be sufficiently known in common life, will senre as an elucidation; or, in the want of such, to derive the denomination from the colonrs composing the mixture, which, at the same lime, wopld explain the Colour.

m ' Brj^caiwn tf the

shall demonsirate a greater degpree of intefisity^ ver- ging on; as e. g. blue indiniog a little to reddish^ yeUowish-green inclining a little to brown, red verging on yellow.

f 46.

Colours may be further determined by the re- lation in which they stand to each other with re- spect to shade. Thus, the princrpal colours differ from one another in shade, and we have light colours as white and yellow, and dark as blue and black : further, the varieties subordinate to each principal colour differ from each other in respect to shade, as e. g. among the blue colours, indigo- blue is dark, azure-blue clear, and sky-blue light ; and even each variety may be distinguished with regard to shade, as e. g. clear canary-green, light canary-green. In general, however, four degrees are adopted as distinctions in the shade of colours, and tfiese are expressed by the words, dark, dear, light, pale.

The shade of colour frequently depends merely on the transparency of fossils ; the paleness of a fossiVs colour being in proportion to the degree of its transparency, and its darkness in proportion to its opacity. Hence several transparent fossils possess lo pale a colour, that several Oryctognostical Writers have described them as colourless; e. g. Bock-crystal, Diamond, Specular-Gypsum. In this, however, an error was committed which rendered

the

External Characters of Fossils. 43

*

the descriptions inaccurate ; for eyery fossil, accord-

uig to the opinion we have adopted, necessarily

possesses a colour, and which may be easily dis«

covered in the very fossils described as colourless^

by merely comparing them with each other.*

The greater or less degree of Lustre in fossils has

also an influence on the shade of their colours.

♦ I . The principal colours with ther varieties,

§. 47.

I now proceed to the explication of each princi- pal colour with its varieties, according to the order of their transitions. Among these the White colour occupies the first place. In Natural Philosophy k is on good grounds considered as pure lights or the sdar ray not divided into its colours. To adduce the experiments which prove this would lead me too far firom my subject ; whoever wishes to read them may find them at large in most books treating of Natural Philosophy. The white colour is among all principal colours the clearest ; and hence, in corn-* parison with others, admits but a slight admixture of another colour. I have already remarked, in the

Note

* The word ewhurku it emplojed in oryctognosy in % double scnie : iBt in f<Mfilt, which, by reason of their transparency, possets an cat- traordinary pale colour, it is accepted in the foregoing signification ; and. several Mineralogists apply it to species of fossils which are mott commonly found white, in opposition to those ▼arieties which possets other colours. As, howerer, in both cases, an indefinitenesi arises in the dctcriptio&s, it it better not to make use of the ex* pccision.

44 Explicatim of the

Note to §. 41| that the White colours^ the metallic excepted, appertain peculiarly to Earths and Stones. We have^

1 . Snow-white ; this is the proper white colour, unmixed with any other. Among fossils it occurs in snow-white Quartz, acicular White-lead Ore from GlUcksrad near Zellerfeld, white coralliform Stalao* tite from Styria, Limestone from Carrara.

2. Reddish-white ; here the white colour is mixed with some little red, and through this variety passes into the red colour, viz. flesh-red ; it is found in Porcelain Earth, reddish white Calcareous Spar, red- dish-white Quartz.

3. Yellowish-white ; in this variety the white colour is mixed with some little yellow, and through it passes into the yellow colour. Many call it also milk-white, because it is the colour of thick cream. It is present in White-Amber, yellowish-white Stalac* tite, Zeolite, Chalk.

4. Silver-white ; this is a metalilic white colour in- clining a little to yellow. Its name is derived from Silver, to which it properly and peculiarly belongs. Among fossils we meet with it in Native-Silver, Native-Bismuth, Arsenical-Pyrites.

5. Greyish-white — is a white colour inclining rather more than the former to yellowish-grey. It occurs chiefly among several kinds of Gypsum, foliated- granular Limetone, and Quartz.

6. Greenish-white — ^is a white colour mixed with some green, forming the transition from white

into

External Characters of Fossils. 43

into green, viz. into apple-green. It is found in Talc, white Amianthus, and the Calcareous-spar reseoibling Talc from the Mine Unvcrhofites GlUck near Schwarzenberg in Saxony, Limestone from the Alte Berg near Schmalzgrube.

7. Milk-white — ^is a white colour mixed with some blue. — Its name is borrowed from skimmed milk, to which this colour particularly belongs.— It is pre- sent in Opal, and milk-white Quartz.

8. Tinjwhite — ^is a metallic white colour inclining a little to blue. It constitutes the transition from the white colour into lead-grey. Its name is de- rived from Tin, in which this colour peculiarly occurs. In the mineral kingdom, we meet with it in White-Cobalt-Ore, Native-Quicksilver, Arseni* eated-Native-Silver, and Native-Antimony.

$. 48.

Grrejft the second principal colour, proceeds from a mixture of white with a little black ; hence it constitutes the transition from the one colour into the other. Consisting for the greater part of white, it is one of the palest of the principal colours. J have already given ray reasons for considering it as a distinct principal colour in the Note to $. 42.

The several varieties of grey arise accordingly as a slight admixture with another principal colour takes place ; they are the following :

1. Lead'grey — this is a metallic bluish-grey colour, appearing to consist of steel-grey with a slight ad- mixture

V

4§ Explication of the

mixture of aziire-Utie. Its name is borrowed frool Lead| to which this Colour peculiarly belODgs. It is one of the most common in the Mineral King- dom, and occurs in Common Galena^ Compact Galena^ Sulphurated-Bismbth, Grey^AntiqioniaUOrey Vitreous->Cbpper-Ore, Molybdaena frdm Altenberg in Saxony.

2. Blueish-grty — difiers from the preceding in want of metallic Lustre only. It is found in blueish^rey Clay^ blueish-greyLimestone, and blueish-grey Marie.

3. PearUgrey — consists of light blueish-gprey with a slight admixture of reddish-TioIet*blue. Present in pearls^ yet rather pale. But in. the Mineral. Kingdom it occurs particularly distinct in Corneous* Silver-ore, pearl-grey Quarts, Calcedony, Porcet* lanite, and Lithomarga. Rarely present in Rock-^ crystal. It borders on Lavender-blue.

4. Reddish'grejf — ^is a grey mixed with much red. It is present in granular Limestone, Felspar, Specular Gypsum.

5. Smoke-grey — is composed of a rather dark- grey, with a slight admixture of blue and very little brown. Derived from Smoke, which is gene- rally of this colour. It is found in dark-grey Flint, grey crystallized Cakareous-spar, grey Hornstone, and grey Fluof-spar from Freybei^.

6. Greenish-grey-^As a light-grey colour, consist- ing, sometimes of very pale yellowish-grey, some- times of very pale smoke-grey, with a slight admix- ture

External Characters of Fossils. 4T

Me of Terdigris-greeDi^ I faaVe met with it only in Prdinitey dtts-eyc. Jargon, and some varieties of ArgilUte.

7. rdhwish-grey — ^is a pale-grey mixed with more or less yellow. It occurs in yellowish-grey Argil- laceoQs-Iron-Stone from Wehrau in Upper Losa- tia, yellowish-grey Tripoli, yellowish-grey Calce* dony, yellowish-grey Indurated Earthy-Lead-Ore from the Mine Rauten Kranz near Johange<Mrgei»» stadt

8. Sied'gr^'^tbis is a metallic blackish*grey colour, and which seems to possess a greater portion of black than either of the other grey colours ; hence it constitutes the tran^tion from grey into black. Derived from Steel, to which it properly belongs. It is very common in the Mineral King- dom. In Specular-Iron-Ore, Striated Grey-Ore of Manganese, Grey-Copper-Ore, Grey-Cobalt-Ore.

9. Ashe^rey — ^is one of the rarest and the purest, of the grey Colours, consisting of yellowish-white and black, and derived from Wood-Ashes not burnt white to which this Colour properly belongs. It occurs the most distinct in Wacke graduating into Basalt, also in Argillite.

$.49.

Black holds the third place among the principal colours. It is considered as the total absence of light This colour occurs very frequently in the Mineral Kingdom, and appears chiefly peculiar to

Inflammable

*4t Explicatum of the

Inflammable sdbstanbes; it is the darkest of tin principal colours^ and on this account the admix-^ tures of other colours are not easily perceived. The few varieties which if possesses, and which proceed from an admixture of other principal colours, are difficultly distinguished from each other ; they are

the following:

1 . Greyish-black — ^in this variety black is mixed with grey. It is also the transition from black into grey, viz. into blackish-grey. Of this colour Wc have black Flint, Hornblende, Argillite, black Limestone, Basalt.

2. Srorvnish'black'-here black is mixed with brown, and passes through it into blackish-brown. We meet with this colour in Wolfiram, Black Blende, Bituminons-Shale, Tin-stone-Crystals^Black-

Cobalt-Ord.

3. DarkMack^thh is the proper black colour, or perfect black, being unmixed with any other colour. It occurs in Obsidian, otherwise called Iceland-Agate, Shorl, let.

4. Iron-black— is a perfectly dark and metallic black colour, occurring sometimes lighter, some- times darker. In the latter case, being dark-black, it is found in Micaceous-Iron-Ore from Tobschau in Upper Hungary. In the former, in which it shews a slight admixture of grey or white, and then also passes into steel-grey, it occurs in Mag- netic-Iron-stone, sometimes in Antimoniated-Silver- Ore, and frequently in Micaceous-Iron-Ore.

5. Greenish^

^

External Characters of Fossih. 4t

. 5. Crreenish^M€u:i'^^onsi9)ts of much black and a little green^ and forms the transition into blackish- green. It occurs in Serpentine^ Hornblende, Pitch- stone.

6. Bluish^black — is a black colour verging a little on blue, and constitutes the transition from the one colour into the other. It is present in Alumi« nous-Shale, Black-Cobalt-Ore, dull Black-Lead- Ore.

§. 50.

Blue is the 4th principal colour, and also one of the darkest. Several Natural Philosophers have con- sidered it as a compound of black and white ; how far this may be. just, and wliether it should not rather be deemed simple, I shall not here inquire. In the refraction of the solar ray by the prism the blue colours appear uppermost.

Blue is the rarest colour in the fossil kingdom, so that we can scarcely exhibit more than eight or ten species to which it is peculiar. It cannot be said tp appertain particularly to one or the other genus of fossils. Formerly it was exclusively ap- priated to Copper ; this, however, has been suflSici- ently contradicted by the discovery of blue in Iron, and in several Earths, Stones, and Salts. Those of its varieties which occur in fossils are the following :

1 . IndigoMue ; this, which is the darkest of the blue colours, and inclining a little to black, consti- tutes the transition from ene into the other. Its

X name

50 Explication of the

BaHie^ is derived from the indigo employed in paint- ing to produce this colour. Blue^-MartiaUEarth, from Eckartsberg, near Weissenfels, in Saxony.

2. PTnissianMue ; this is next to indigo-blue die darkest bide, and not inclining to any other colour may properly be called perfect, or pure blue. The denomination is derived from prussian- blue, a painting colour, nvitfa ^bicb it coincides. I have never met with the proper or dark prussian- blue in the fossil kingdom ; but of the light prussian- blue we have Sapphire, and blue Rock-salt.

3. ^zureMue ; is a clear and flamy-blue, inclin- ing a little to red. The name of this colour is borrowed from Lapis-lazuli, from which the valu- able painting colour Ultramarine is prepared, and with which it coincides. It is present in Lapis- lazuli, and dark Azure-Copper-Ore.

4. Violet'blu€y or violet ; is a rather clear reddish- blue colour, and appears to consist of a mixture of azure-blue and crimson-red, into which two colours it also forms the transition. It is the uppermost colour' among those produced by the refraction of the solar ray io the experiment with the prism. We meet with it in violet blossoms, whence the denomination is derived. In the fossil kingdom it occurs 10 Amethyst of every degree of shade, Fluor- spar, Lithomarga (the well known Terra miraculosa Saxoniccj) Spinell-Ruby, and more rarely in Calcare- ous-Spar, and Apatite, also in Rock-salt.

5. Lavender-

External Characters of Fossils, 51

5. LavenderMiUy is a pale blue colour, composed

•

of a mixture of very light violet-blue verging a little on reddish, and a little blueish-grey. It oc- curs sometimes in Lithomarga, but chiefly in a* Porcellanite from Schweinschiitz and Stral^ke in Bohemia. It stands mid-way between pearl-grey and violet-blue.

6. Smalt^hlue ; this is a rather light blue colour, and appears to consist of azure-blue mixed with a little white. Ip the experiment with the prism it stands between violet and sky-blue. Its name is borrowed from the well known Smalt, from which this colour is produced for painting — Light Azure« Copper-Ore, light Blue-Martial-Karth from Nieder- leschen near Sprottau in Silesia.

7. Sky-blue ; is a light blue colour, which in- clines some little to green, and constitutes the transition from blue into gr^n, viz. into verdigris- green. Painters call this colour also mountain-blue. The denomination is derived from the colour of a clear sky* In the experiment with the prism, which has been so frequently mentioned, this colour is also produced and appears between smalt-blue and grass-green,. into which last it gradually passes. It is found in light Azure-Copper-Ore, blue Natu* ral-Vitriol, and sky-blue Fluor.

§. 51.

We new come to Greeriy the 5th principal colour. It is a clear mixed colour, composed of blue and

£ 2 yellovr,

52 Explication of the

yellow, and forming the transition from one into the othen In the refraction of the solar ray by the prism, a kind of green is also obtained, which is a medium between grass-green and canary-green. It there appears between sky-blue and lemon-yellow. Green is not very common in the fossil kingdom, yet it occurs much more frequently than blue. It appears to belong in particular to Copper ; Lead, however, and several other Metals, and many Earths and Stones, also lay claim to it. Its varieties oc- curring in Fossils are the following :

1. Verdigris-green; which is a clear blueish- green colour, in whose mixture yellow is not per- ceptible. It forms the transition from green into blue. It coincides in colour with the verdigris known in common life, and hence the denomina- tion has arisen. It is present in Green-Copper- Ore, verdigris-green Fluor.

2. Celadon-green ; is a clear blneish-green co- lour, composed of verdigris-green and a little ashes- grey. In its mixture not the slightest tint of yel- * low can be perceived. We find it in some Bra- zilian Berylls, and in the pure Green-Earth from Brentonico*

3. Mountain-green; is a light and almost grey- ish-green colour, appearing to consist of light ce- ladon-green, with a little yellowish-grey, and also a very little white. Here a tint of yellow may already be perceived in the mixture of the colour; b]ue, however, still predominates* Its name is

borrowed

External Characters of Fossils, 53

borrowed from a painting colour with which it nearly agrees. It passes into greenish-grey, and thus constitutes the transition from green into grey. Among Fossils, it occurs in green Hornstone from Altenberg, Saxon Aquamarine, most Berylls, Ac« tynolite. •

4. Emerald-green ; is a clear pure green. It seems to consist of equal parts of prussian-blue and lemon-yellow. The denomination is derived from the Emerald in which this colour is particu- larly distinct; it is also found in Fibrous Mala- chite, and Fluor-Spar.

5. Leek^green; is a dark green colour inclining a litde to brown, and which appears to be a mix- ture of dark grass^green, a little brown, and a very little ashes-grey. Its name is taken from the leek. • It nearly agrees with the sap-green of painters. Of this colour we have Pr^um from Breitenbrunn, near Schwartzenberg in Saxony^ most Jade, Asbestus from Zoblitz, ActynoUte from Krebsberge near Ehrenfriedensdorf.

6. Apple-green ; is a light green colour incline' ing much to white, and forming the transition into the latter. It is composed sometimes of eme- rald-green, sometiihes of grass-green, and white; TUs C(Jour is peculiar to some kinds of apples, whence the denomination is derived. In the fos- sil kingdom it occurs in Cbrysoprasium from Co- semlitz in Silesia,' green Common Opal from the

same

54 f Explication of the

same place, Prehnite from the Cape of Good Hope, and Nickel-Ochre.

7. Grast^reen ; ia a clear pure green, in wfaioh yellow, howerer, already predominates. It bor^ ders on emerald-green, leek-grecn, app]e*greei», and pistachio-green. The denomination of this co- lour is derived partly from the young growing gras of Spring, partly from that grass which in Summer is found in the vicinity of springs. In the mineral kingdom we find it in some Chrysou prasium, and some Green-Lead-Ores.

8. PistachiO'greeji ; is a grass-green, perceptibly verging on yellow, and mixed with a very little Uue* In the mineral kingdom, it occurs in many Tourmalines from Brazil, Bohemian Chrysolite, and Earthy and Glassy Iron-Sbot-Green-Copper-. Ore from Saalfeld, when unmixed with yellowish ]Prown4ron-Ocbre. Pale pistachio-f^es approaches to asparagus-green^ clear to grass-greeo, and dark ^ leek^reen*

9. Asparagtis-greem is a pale yellowish^green^ minted with a little brown apd grey. It has re- ceived lis name from tb^ asparagus stalk. In the mHiheral kingdom^ we mee^t. witt^ it in Chrysobe* ryll,. some Siberian Beryljs, Green-Martial*Eanb from K()lbcr near Schneebefg, and in a rave i«ir riety- of Green-Lead-Qre^ from the country bf Triers. The colour, however, of the Grten^Mar- tial-Earth l4>prx>£hehes rath<^r to canary^green.

iO. Oliv€-

Externti Characters of Fossils. 5S

10. (Mwe^grem-, is a light green colour rerg- ing coiMtderaUy on broWta, and which seems to tMnsfc of clear caoary-gi^een and mueh brown* it is foimd in moit ' Green-Lead-Ores, many *Ser« pentineSy among others that of Saatburg in Swe- den, Actyndite from Bwrg d^Oiseau in Danphiny, •dme Chrysoprasiumi Hiany Pilch-stones^ Grarnets, Caicareous-sparS| a«d other Fossils.

11. Bhukish^een ; is a very dark leek-green mixed widi mnch black. It occurs almost solely in the dark grc^n Serpentines.

Ifi. Camary^een; n a rather light yellowisIi«> greea coionr. It constitnles the transition from grem into y^ow, riz. into sulphur-yellow. The denomioation is taken from Canary birds in which it particularly occurs. Among Fossils it is pre^ sent in Green-Lead-Ore, Micaceoa»-Uranitie-Ore, green Steatiict fipom ZoUita;

§. 52.

Yellow^ being the sixth, is a very light princi^ pal Colour. Of its varieties two are produced in the refractioQ of the solar ray by the prism, ap- pearing between green and red.

Yellow is rather frequent in the fossil king-^ dom, but not peculiar to any particular genus of Fossils. The varieties which occur, according to the different admixtures of other colours, are the following.

1. Sulphur^

.S6 Ejppticatian of ih^

1. Sulphur-yeUow ; which is a light greeninlvyel- low colour. It forms the transition from yellow into green. The denomination is borrowed firofn Sulphur in which this colour particularly occunk We 6nd it in Natural-Sulphur, and sulphur-yellow Serpentine from Zbblitz in Saxony.

2. Lemon-yelhw i is a dear pure yellow. To produce this colour painters make use of Gum Guttoe. Derived from Lemons, with the colopr of which it agrees. In common life it is also .called gold-yellow ; but this belongs more particularly to the following Qolour. In the refraction of the solar ray by the prisqa, which has been so frequently mentioned, it appears between green and orange- yellow. We meet with it in Orpiment, and some Yellow-Lead-Ores.

3. Gold'i/ellowi this is a metallic clear yellow, colour, in which an admixture of another colour is not perceptible. Excepting the metallic lustre^ it agrees perfectly with the preceding colour. Bor- rowed from gold ; to which this colour is peculiar. It is found in Native-Gold.

4. BeU-MetaUTelltyu) ; this is a metallic pale yel- low colour, inclining very little to reddish ; it seems to consist of pale gold-yellow^ very little brownish- red, and grey. Derived from bell-metal, with the colour of which it agrees. We have bell-me- tal-yellow Martial-Pyrites.

5. Straw-yeUow ; this is a pale yellow colour, composed of sulphur-yellow and a little reddish-

Exterml Characters of Fossils* 51

grey. It is particularly found in straw, whence the denomination is taken. In the fossil kingdoni k ocGurs in yellow Jasper from Lessa, near Carls- bad^ in Bohemia; Calamine, and Bismuth-Ochre.

6. Wine-ycllow : is a pale reddish-yellow colour, appearing to consist of pale lemon-yelFow, and some little brownish-red. We find this colour- in yellow, or white wines, whence the denomination is borrowed. Among Fossils, it is present in Topaz from Schneckenstein tiear Auerbach in Saxony, yel* low cuneiform Calcareous-spar from Poland.

7. Isabella-yellow ; is a "brownish-yellow colour verging a little on grey, a{>pearing to consist of pale orange-yellow, some reddish-brown and a little grey. Of this colour is Calamine, Mountain- Cork from Schaller near Johanngeorgenstadt, yel- low Sparry-Iron-Ore, yellow Bole from Stragau in Silesia.

8. Ochre-yellow ; is a rather dark yellow colour, consisting of lemon-yellow and a little brown. It 16 found in yellow Iron-Ochre, from which its name is derived, most yellow Jaspers, Calamine*

d. Orange-yellow ; this is a dark reddish-yellow colour, seeming to consist of lemon-yellow and rei. It forms the transition from yellow into red, viz. into aurora-red. In the experiment with the prism it appears between lemon-yellow and red." We have orange-yellow Amber, orange-yellow Car- nelian, orange-yellow Calamine; of this colour is also the streak of Realgar, and Red-Lead-Ore.

10. Hony

$9 ExplkaUon tf the

10. ffonejf'jfelhw > is a rather clear j^Ucm colour, appearing to consist of sulphur-yellow and more or less reddish-browD. Derived from honey, with the cdou: of which it coincides. We meet with it in most Amber, honey-yellow Fluorrspar, koney- yellow Opal, Calcedony, and Calcareous-spar, some* times also BerylL

lU Wax-yellow ; is a light honey-yellow, mixed with a little light ashes-grey. This colour is naost distinct in fresh onblanched wax, whence the name is taken. It occurs principally in Yellow- Lead-Ore, yellow Common Opal, and Calcedony.

12. Brass-^4llow i a light metalUc colour, com- posed of gold-yeUow and a little green. It rergea Bometimei more, sometimes less, on green. It is peculiar to Copper-Pyrites, particularly on the fresh fracture, and brass-yellow Natire-GoU, which is argentiferous.

§. 53.

Jled is a simple and rather clear principal colour, and in order the seventh. In the experiment with the prism, it is dbe lowest among the colours.

It is one of the most common colours in the fossil kingdom, and seems to be particularly appropriate to Iron. According to ths several admixtures of other colours we have the following varieties :

1. Morning f or aurora-red ; is a clear yellowish- red cdour, con^posed of scarlet-red and orange- yellow. (See Sctueffers' sketch of a general display

of

Extemul ChanUiefs iff Fossils, 59

of Colours Tab. IL Numbei' U) It tonstitiitds the tranatioi] from red ^nto yeUoW. In paintlQg it » jiroduced by Minium. Derifed from the colour of the morntDg d&wn with which it agrees. Of this cotour we haye Red^^Lead^Ore from Siberia^ Rcalgat, and in some spots Yellow Blende from Scharfenberg^ 3. Hjfocinthjred I is a clear red colour mudh Te- sembling the former, and diffiirtng chdIj in a ^ight admixture of brown. In Red-Lead*Ore, a vari^jr of Brown Btende, Hjacfntb.

3. Brici^red ;- ift a light red Colour, composed of aurorarTedi a Uttle white, and very little brown* It occurs m newly burnt bricks whence the name ift taken* In the Mineral Kingdom we find it distinct, in a variety of Porcelknite from Strakke id Bo- bemiaiy occasionally also kk Jasper and Pitcfastoweu.

4. ScarleUred ; is a clear red c<^ur inclibing a little to yellow, and seems to consist of ciini8dB«>ici(I and a little lemon-yetlow* (See Scbcbficrs' Sketch eV a general Display of Colours, Tab. 11. Number 9.) To produce this colour painters make use of Ciniuu bar. It is the same red as that obtained in the re- fraction of the solar ray by the prislD. It is found in light red Cinnabar from Muschiellandsberg lA the Palatinate.

5. Copperrredi it a nieiaBic light yellowish-red colour. Derived from Copper, wkh the colbov of which it agrees. Is is present in Natif«-Copper, and Sulphurated Nickel; this latter, however, in- dines a little to silver-white.

6. Bloods

60 Explication of the

6. Blood-red ; is a dark-red colour, appearing to consist of crimson-red and scarlet-red. Its denomi- nation is taken from Uood, to which this colour is peculiar. It occurs in Bohemian Garnet, red CameUan, and Quartz from Compdstella and Va-' lencia in Spain.

7. Carmine'red ; is a clear red colour, in which an admixture of another colour is not perceptible,' and may therefore be considered as the proper or pure red. (See Schoeffers^ Display, &c. Tab. II. Num. 4 :) Deriyed from the carmine-red of painters. Among fossils, we meet with it in Capilliform Red- Copper-Ore, clear red Cinnabar from Hartenstein near Schneeberg, and from Rosenau in Hungary.

8. Cochineal-red; is a clear and almost dark-red coloor, and appears to consist of carmine-red and a tery little blueish-grey. Borrowed from cochineal. Cinnabar generally occurs of this colour, sometimes also Jasper, red Quartz, and Ruby.

9. Crimson^red ; is a clear blueish-red colour, which seems to consist of carmine-red and some prussian-blue. (See Schoeflfers* Display, &c. Tab. II. Num. 2.) It constitutes the tranrition from red into' blue, viz. yiolet-blue. Of this colour we have Ruby, Oriental Garnet, Striated Red- Cobalt- Ore.

10. Coktmhine^red ; is a dark blueish-red colour, consisting of a mixture of crimson-red and a little' blue. Blue predominates here more than in crim- son-red. Derived from the blueish-red colour of

the

Extermd Characters of Fossils. 61

the PigeoD^s-neck. It occurs in precious Oriental Garnet, Striated Red-Cobalt-Ore.

11. Flesh^rcd; this is a pale red colour, com- posed of crimson-red and yellowish-white. (See Sfaceflfer, &c. Tab. II. Num. 110.) It agrees with the colour of the human flesh , whence the de* jiomination is derived. It occurs in flesh-red Baro* selenite, flesh-red Felspar^ red Gypsum, red Quartz^ red Lithomarga.

12. Rose-red ; is a pale red colour, composed of cochineal-red and a considerable portion of white. Chiefly in Red-Ore of Manganese from Kapenick in Transylvania, rarely in Striated Red-Cobalt-Ore, red Zeolite, rose-red Quartz, Ruby, and some Siderocalcites.

13. Peach-bhssom-red ; this is a light red co- lour, composed ' of crimson-red and snow-white. (See Schsefier, &c. Tab. II. Num. 71.) Derived from the blossom of the peach, with the colour of which it coincides. It is present in Striated and Earthy Red-Cobalt-Ores.

* 14. Cherry-red ; is a dark red colour, composed of crimson-red and a little yellowish-brown. (See Schsffer's, &c. Tab. II. Num. 6.) Among Fossils it is found in Red-Antimonial-Ore from Brauns- dorf near Freyberg in Saxony, red Scaly-Iron-Ore, and a variety of Ruby.

15. Brownish-red ; is a rather dark red colour, composed of blood-red and some brown, and forms the transition from red into brown. (See Tab. II.

Num.

€2 Explication of the

Num. 8. of Scfateffer^s Sketchy Au;.) We meet with it io red Argillaceous Ironstone from Webrau in Upper Lusatia, Red jasper-like Ironstone, Red-Ironstone of loose earthy consistence*

§. 54.

The eighth and last principal colour is Br<mn% being a mixture of a little yellowish-red and black, and forming the transition from one into the other. It is the darkest colour next to black.

It occurs rather frequently among Fossils, and 10 particular among Iron-Ores and Inflammable Substances* In the mineral kingdom we have the following varieties of brown :

1. Reddish-brown; is a clear and almost dark brown colour^ verging closely on blood*red. It is present in brown Tinstone, and Brown Blende^ rarely however.

2. CUrve^hrown ; is a dark brown colour, verg* ing almost imperceptibly on carmine-red* Deriv-* ed from cloves, with the colour of which it agrees. It occurs in Compact Brown-Ironstone, brown Spar-- ry-Iron-Ore, brown Rock-crystal from Zinnwald in Saxony, rarely in Amethyst, but in most Thumer. stones from Dauphiny.

3. Hair 'brown; appears to be a medium be* tween yellowish-brown and clove-brown, with a slight admixture of grey. Of this colour we have Wood-Tin-Ore from Cornwall^

,4. Yellowish

• Extemal Characters of Fossils. ' 61

4. TeUowish-broxtm; is a light brown colour^ ▼erging on ochre-yellov. It constitutes the tran* sition from brown into yellow. We find it in Brown Iron-Ochre, SwampyJron-Ore from Sprottau in Silesia, Jasper.

5. Tanibac-brown : this is a metallic light yel- lowish-brown colour, which seems to consist of gdd-ydlow and reddish*brown. It much resem- hUs Uraished tombac, from whicfa the name is taken. It is found in brown Mica.

6. JVood'irinon; is a very pale colomr, being a mixture of yellowish-brown and much ashes-grey. Distinct ia half decayed wood, Bitiuniootts»Woody and a variety of Asbestus,

?. Lwer-ir^wni is a light brown colour, eon* sisting of blackisb-brown inclining a very little to green. It is the colour of livers, whence the name is borrowed. Among Fossils, we naeet with it in Browo-Ck^lt-Ore, brown Jasper from Auerswalde near Chemnitz in Saxony.

8. Blackish-browH ; is a dark brown colour veig^ ing on black, and constitutes the transition from brown into black. Blackish-brown Lowland<-Ar« giUaceous-Iron-Ore from Oelsse near Saagan in Silesia, Mineral-Pitch, Bituminous-Wood, Onyx.

§. 55.

These are the several varieties, by which the colours of Fossils may be determined ; but, al- though I have collected a considerable number, I

wilt

64 ' Explication of the

will not deny that several others may be disco- vered by future experience. Should this, faowe- ' ver, even take place, it will no longer be difficult to give to ^he new colour a systematic denomina- tion^ to determine its conception, and to appoint it a proper station in the system.

§. 5Q.

There are several Fossils which cannot be said to possess any certain variety, of colour, such be- ing either a mean between two colours, (as e* g. Compact Malachite, the colour of which is a mean between verdigris-green and grass-green; Micace- ous-Uranitic-Ore, which is a mean between grass- green and canary-green ; yellow Earthy-Lead-Ore, between sulphur-yellow and lemon-yellow ; yellow Carnelian, between lemon-yellow and wine-yellow ; Magnetic Pyrites, between bell-metal-yellow and copper-red ; Red-Silver-Ore, which is generally a mean between crimson-red and lead-grey, &c. ;) or inclining a little to a different colour, (as e. g. White-Copper-Ore> whose silver-white colour in- clines a little to gold-yellow; Red Hoematites, whose brownish-red colour inclines to steel-grey.) These are said to be of that colour to which they bear the nearest relation, and the extent of varia- tion is afterward determined, as e. g. Oriental Garnet, whose crimson-red colour verges a little on black, Vitreous-Silver-Ore whose lead-grey co-

lour verges on black.

2. The

JSxternal Characiers of FbssUs* * 65

2. The Shade of Colour. §. 51.

I have already mentioned in §• 46. of this Chap.

that the shade of every variety of colour occurring

in a species or variety of fossi], may be further

determined by saying — e. g. green Hornstone is

clear mountain-green. Aquamarine is pale moun*

tain-green y Bohemian Garnet is dark blood-red| ^ed Camelian is light blood-red.

3' The tarnished colours^

The tarnished colours are charactaristic of sere* cal fossils. In saying a fossil is tarnished we mean^ the colour of the surface differs from that of the fracture*

These tarnished colours proceed -from di£Eerent causes ; either from an incrustation by another fossil, as variegated tarnished Copper»Pyrites, yellow tarnished Native-Silver, both of which ar« slightly iQCjnisted with an Iron-Ochre ; or froraP.a change in the chemical (constitution of the fbssil^s surface^ and which may take place in a two fold manner, viz. either by its entering into combination with an cc(traneous substance, (as black tarnished Native- Silver, which has become united to sulphur,) or by losing one or more of its constituent parts, (as hiack tarnished Native- Arsenic, variegated tarnished

F Native*

66 Explicatidn of the

Native-Bismuth ;) in both' which cases the tarnished colour proceeds from a loss of the inflammable principle.*

Some fossils occur tarnished in their natural po^ sition only, in the place of their formation, as Com- mon Galena, the drusen|| of which are fre(|uently found tarnished in fissures, as also Blende, Qrey- Antimonial-Ore, Specular-Iron-rOre. The fresh fracture of either of these dpes not tarnisb.

Other fossils tarnish on every fresh fracture that is made, as Native-Arsenic, Grey-Cobalt-Ore, Na- tive-Bismuth, Copper-Pyrites.

Others again, are always tarnished, both in the place of their formation^ and on their fracture. The most striking examples are— -Purple-Copper- Orc, Native-Bismuth, Native-Arsenic.

With respect to the colours themselves which tar* nished fossils possess, they are simple or variegated. Of the former we have :

1. Grey, which is the tarnished colour of Whitc- Cobalt-Ore, and steel-grey of Browq Haematites.

2. Blacky the tarnished colour of Native-Arsenic* (which is- properly of a light lead-grey colour,) 3r6wn Haematites, and Grey-CobaltrOre.

3. Brown^

^ It may be obncrred here, and occasionally in the following pages, that at the time this was written the phlogisde theory or Stahl was in general acceptation. tk. .

II The German term drwemf for which wc have no correspondiog English word, |ias been already adopted in the English Language. It- sgnifies an asAemblage or group of crystals protruding fhna tlM same surface. See in the eequd §^x67> f^t the definidon pf ttnuy.

External Characters ef Fossils. n

3. J^rawfif of Natire-Silver^ ivhich is properly «ilTer-white,

4. Reddishj of Native-Bismuth, if free from Co* bait. Its fresh fracture is silver-white.

5. TeUowish^ of White^Cobalt-Ore, Argentiferous* Arsenical-Pyrites. Of the variegated we have —

1. Pavontne-tamishedf which is an assemblage of yellow, green, blue, and red of nearly equal p^rts, with a dark shade of brown, somewhat similar to Uie colours of the peacock's tail. Blue and yellow generally predominate, and yellow seems to be the ground colour. The c(dours are never pre- cisely distinct, but . always pass more or less one into the other. It principally occurs in Copper* Pyrites, Purple-CopperrOre, Common Pyrites.

2. Iridescent-tarnished J which consists of blue, green, yellow and red, in nearly equal proportions, bearing some resemblance to the colours of the raiii*- bow. Blue seems rather to predominate. It is chiefly present in grey fossils, but beautifully so in the Grey •Autimonial- Ore from Felsobania in Hungary, also in Martial-Pyrites, Galena, Specular-Iron- Ore, Arsenical-Pyrites, Hepatic Pyrites, and - Brown Haematites,

3. Columbine-'tarmshed consists of the lightest shades of white, red, green, very little yellow, and blue, and much grey, resembling in some measure th^ varied shades of the pigeon's neck. It occurs the most distinct in Copper-Pyrit^

T% 4. SteeU

6S Explication of the

4. Steel'Cohured'tamished consists of mucb grey^ blue, red, yellow and green, representing the colours of hardened steel. This is also chie^y found in grey fossils, and occurs in Grey*CobaIt-Ore.

4. The play of colour.

$. 59.

The Play of colour is not observable but in sun« sbine, or some other strong light. By it is under-r stood the property which some more or less trans-* parent fossils possess of refracting in certain spots the incident rays of light, producing iridescent colours. This refraction of the solar rays originates in the peculiar association of the molecules of a fossil ; frequently, however, it arises from acci- dental causes, such as slight rifts, cracks, &c. In the play of colour the Diamond is eminently dis^ Anguished, sometimes also Rock-crystal.

5. The mutable reflection of cohmr^

§• 60«

The mutable reftection of colour Is distinguished from the play of colour by the fossil displaying in the same spot a variable colour accordingly as the angle of the incident rays of light is varied. This change takes place either on the surface of the fossil, or internally ; and is perceived by varying its position in relation to the eye, or by holding it \Yp to the light, The superficial mutable reflection

of

External Characters of Fossils. 6f

of colour is particularly beautiful in Labrador stone^ and Marble with variegated Petrifaction of Shells ) the intemalj in Precious Opal, Moonstone, and Cats-eye ; though indeed in the two latter it is rather a mutable reflection of lustre than of colour* By holding up to the light also semi-transparent Common Opal, whose colouf is milk-white, it ap- pears wax-yellow, and oriental milk-white Moon-> stone appears red, which may be thus distinguished from that brought from Switzerland 4

6. The mtUation of colour*

The mutation of colour differs from the tarnish m this respect, that as in the latter the surface of the fossil alone undergoes a change of colour, so in the former the change penetrates into the interior of the fossil, and sometimes even pervades the whole. Of this we have two modifications :

1. The fading of colour, by which is meant that a colour b become paler by light, heat, moulder- ing of the fossil, and other external causes. Thus striated Red-CobaIt*Ore by elcposure to the air be-» cooies pale brownish ; blue Fluor-spar, green ; Chrysoprasiutn, light green; pearl-grey Corneous* Silver-Ore^ clear brown.

2. The perfect change of colour*^thi9 is not un* frequently a consequence of fading, and means the loss of one colour, and the production of another*

Such

76 Explication of (he

Such a change is commonly undergone by Sidero- calcite, tight coloured Sparry-Iron-Ore, Earthy Grey-Ore of Manganese, Argillaceous Ironstone.

7. The delineations cf Colours^

§. 62.

The delineations of colours proceed from a mTsr- ture of diflFerent varieties of one species,* and take place^ when a homogeneous fossil contains in one and the sanie specimen several colours passing through its interior, according to certain delinea-: tions. The following are the most common.

!• Doited'^FiQe points of another colour* We have dotted Serpentine, and Jasper. Heliotropium and Agate are not dotted, as their points arise from interspersed Jasper.

2. Spotted'^omts from the size of a lentil ta

»

that of sixpence* The spots are round and regular,

or

* The classing of a mixture of several rarieties of one species as i particular variety, or— stUl more unpardonably— a nuxtnreof diflerent species as a particular species, are errors which crept into min^ ralogy at a time when this science rather resembled the accumit- lated knowledge of artificers in metals and stones than a brancbr of oatural history. That artificers in stones gave rise to these errors ia evident, as they occur in suCh fossils only as came within their fphere, viz. Agate, Sardonyx, variegated MaoAiles, 3cc.; in othert <n the contrary, such as several Ores which occur in miztiires» they sire not found. Many similar errors in Mineralogy might be mentioned, which by reason of their long standing seetn to have ac- quired a sort of right to their particular places, luch aa the di»* tiActigo into metals and semi-metals, &c.

External Characters ef fossils* 71

of irreguUr ; very distinct ia some Argillites, and Serpentines — irregularly spotted is marbl^ from Bayreutb>

3. iVe^/(pttj— Large and irregular spots, forming with the ground-colour mixed colour^, resembling clouds, tt occurs if) Jasper, Calcedony, Litbo- marga.

4. FUtmy consists of large spots drawn in one direction, and terminating in sharp points. Some Marbles and Jaspers.

^. Striped SLTises when large spots, drawn in one direction, extend to, and run parallel through, the whole specimen. It is straight or curved, and broad, or linear, Btoad and straight striped Jasper, linear striped Agate, Calcedony, &c.

6. Annular consists of stripes forming concentric circles. It occurs in Jasper, Carnelian, and Flints. When the annular becomes angular it bears some I resemblance to a fortification, which is not uncom-

monly founil in Agate and Calcedony. I 7. Dendritic consits of a trunk-like delineation^

I separating into larger and smaller ramifications*

Found in some Limestones, Bayreuth Steatites, Egyptian Marble, Calcedony, &c. It differs widely firom the dendritic delineation to be found on the surface of many fossils.

8. Ruinous, a delineation in which a resem- blance to ruins may be easily conceived. Seme paralleL unifomly coloured stripes, over which

others

12 Expticaium of the

others esctend in an horizontal direction form tfaht appearance. Florence Marble.

9- Veiny — consists of narrow difierentljr colonrerf stripes, which cross each other in more er less straight-lined different directions, sometimes form- ing a kind of net. It occurs freqaently in Ser- pentine, and Marble.

2. The Cohesion of the particles^

>

The Cohesion of the particles is the second corn* mon generic character observable in fossils by the sight; also partly and peculiarly by the touch. By the sight, in as much as we perceive it in their external appearances; by the touch, when we examine them with our band, as the common organ of feelings

§. 64.

In fossils, as in all other substances^ we ca)l cohesion that attractive power by which their in- tegrant particles* cohere together, and by which

they

* It it very common to speaJc of t&e fori* of bodies m difie- rent scniei, yet not distinguishing them by the denomination, whick produces great confusion. To avoid this, I shall call those parts which are .obtained by the usual mechanical divisions, and which iure still aggregates, a^rgregaiti paTi$^ Those of which the foregoing are aggregated, and which if they could be actually obtained, would be no farther divisible without changing the

nature

External Characters of Fossils. T$

they more or less resist the force applied io se- parate them.

If the molecules of a fossil be bpth coherent, and immoveable, or difficultly moveable, one among another; as in Flint, Vitreous-Silver-Ore, Martiaf- Pyrites, Chalk, &c. it is said to be solid. If co-. berent^ and likewise easily moveable one among

another ;

■ature of the body, bittirant pariicUt Of wnlecmUs, T&OtC which form the conatitation of the integrant particles, but which are themselvet combinations, eotutHment parts. And lastly those whicH compose these constituent parts, but which are neither combiaa* tions, nor aggregates, but rather simple parts or unities of mat* ter, I shall call primitive cottstitMemt parts. An example by way ef illustration; let a piece of Sulphur be divided in any mecha- nical way, all the parts obtained are mfgrtgaUd parts. If cack of these could still be so far divided as to cease to be an ag- gregate, and were a t'umpU parfitU of Sulphur only, it would be •a imtsgroMt partitlc^ or muIscuU. Bach tudt simple pasticle cai^ ■ot possibly be further divided and still remain Sulphur; yet, it is composed of ceruin parts different from Sulphur, namely* Vitriolic Acid and the Inflammable Principle, into which it caa be resolved ; and such parts, into which combinations are daily resolved in the L.aboratories of Chemists, are cotutitutni pari*. But, these constituent pans are still furthei* composed of ccr** Cain wholly simple parts, vehfch are primitvot mutitueat parts, or, as they are sometimes calTed, elcmsnts.

As by dividing an aggregate part of a body we farther obtaia aggregated parts; so may we also sometimes resolve a consti- tuent part into farther constituent parts. The molecules, and the primitive constituent parts of a body are both simple, with thii difference only; the former, with respect to the aggregation, being no further divisible; the latter, with respect to the con- stitution, which cannot be further analysed, and still Hess mecha- nically divided. Both kinds have this in common that they can- not be made sensible, and that the conceptions which we caa form of them arc merely ab^ract.

14 £xpUcaiion of the

another; as iii Native-Mercurj, and Petrol^ it Is said to be fluid.*

§. 66.

Solid fdssih are distinguished into solid in a rc-^ strictive sense, ^nA friable. A fossil is solid if its individuals always donsitute a single aggregation only. Friable, if it consist entirely of small aggre^^ gations, and so smalt that not one can be indi^ Tidually examined, (for otherwise it would be solid,) but may be considered, in a manner, as molecules of the fossil, and which cohere not at all, or very slightly, together^

§.67.

I should now describe id what manner solidiitff friability, and fiuidityy are examined and deter- mined. But, as these three properties arc partial-^ lar generic characters, of which the first pertains to solid fossils, the second to friable, and the third to fluid, and each of these kinds of fossik possesses

more

* If the t>aiticle8 of a hoAf be lo weakly coherent one among another that their wtight alone» and eten the weight of so small m maM at that of a Jroj^, be tufficient to destroy their coherence, the body u said to htfuid. Hence it may be seen that there afe variable degrees of ftdtfUy as well as of solidify, but which have aot been distinctly determined. However, a body may be said to be the more fluids the smaller the drops are, and the more msily and fwicUy their separation from the whole mass is effected. la other respects it is necessary to dbtinguish /uiJ from liguid; it is this latter which is properly the subject of our present consideration ; whereas under the 'general term of fnidr are UA* derstood all tlMsHt fluidi, and consc^scDtly all aeriform fluids^

Exterruil Characters fif Fossils. *nt

nfore of these characters, I refer them to their proper places, in which I shall separately treat of the particular generic characters of each of these kinds of fossils, and in the order in which they strike the senses.

1. PARTICULAR GENERIC CHARACTERS

Of Solid Fossils.

§. 68.

Sblid fossils may be distinguished by many more External Characters than friable, or fluid ; several properties not occurring in the two latter, which are discriminative marks of the former ; as in fria- ble, the external surface ^ transparency ^ &jc. ; in fluid, the fracture, streak, &c. From this, how- ever, we reap the greater advantage, as there are a £ir greater number of species and varieties of tdid fossils than of friable or fluid.

§. 69«

According to the order which we have adopted^ we shall commence with those particular generic characters of solid fossils which are observed by the sight; then will follow those which are ob- served by the touch, and lastly those which are observed by the hearing. Among those observed by the sight, we first perceive the external farm, then the external surface^ the external lustre, the

internal

16 £xplication of (he

internal lustre ^ the fracturcy tbe/ariw of the frag'^ merits f the form of the » distinct concretions, tb« surface of separation, the lustre of separation, the transparency, the streak, and lastly the j/ain«

§. 70.

The particular generic characters observable by th& Eye in solid fossils are of three kinds ; for some as the external form, the external surface, and the external lustre, are observed in the exterior of a fossil only, 'and hence these three are collectively

* termed the external appearance* Others again, as the internal lustre, the fracture, the form of the fragments (which constitute the appearance of the

fracture,) the form of the distinct concretions, the surface of separation, the lustre of separation (which constitute the appearance of the distinct concretions,) can be observed in the interior of a fossil only, and hence are collectively termed the internal appearance* And others, as the transparency, the streak and the stain, may be observed both in the exterior and interior of a solid fossil, and hence are termed the general appearance.

ill.

The complete surface which a solid fossil has received from nature is called its exterior; thus the natural surface of a specimen of Galena which has been found detached, or inhering in anotlier fossil, is called its exterior ; and hence all the cha- racter

External Characters of Fossils. t^

liters which can be observed by the sight in this surface only are called the external appearance of a fossil.

But as specrmcns of fossils occur, which no longer possess their natural surface or exterior— as e. g. if the forementioned specimeu of Galena were broken, so that no part of its natural surface should be re- tained— it follows that those external characters of solid fossils, which belong to the external appearance^ cannot be observed in every specimen.

To the external appearance appertain, as al- ready observed in the foregoing §., the external form, the external surface, and the external lustre.

The external appeahance.

1. The external form^ §. 72.

The external form of a solid fossil is nothing^ more than the figure of that^ natural surface which its primitive individuals are found to possess.

Solid fossils have either received this external figure in their formation ; or acquired it gradually from other natural circumstances ; such as the rounded fragments of siliceous and other stones, which in general are called pebbles.

Now, those whose external figure originated ia their formation either had space sufficient to form themselves in a manner suitable to their nature ; or

tbo

m ExpUcaiian of the -

the ^pace whkb remained unoccupied by other fossils, and of which they possessed themselves in their production, wias the cause of their externa^ figure ; or they formed thensseives in and with

I

(ither fossils which were produced at the same time. The difforeace of the external figure of those which possessed ample space for their forpiation (and to vhieh all crystallisations, several kinds of particu- lar forms, as dentiform^ dendritic^ stdactitiform^ and lastly of common forms some kinds of nuusm^ Mong) arises; ist» from the different constitution pf their integrant particles, accordingly as dmring their production they differently attracted and united with each other in their solution, and ac- quired different gravities (which have a materia} influence) ; 2dly from the different solvents, and the kind of solution in which the fossils occurred accordingly ^a it was more or less intimate, ^ind . the different precipitants, which all coQtributed to I»roduce a diversity of form ; 3dly from the attraction of the wa}ls, or sides of the cavity, cleft, or fissure, in which tl^e fossil originated, which also produced an effect, in as much as it acted upon the dissolved particles at the time they wera disposed to coalesce or associate together. The different external figure of those which formed themselves according to the space which they occupied, (and to which among particular forms the cellular, among coqamon forma jthe interspersed^ and often also the massive belong,) proceeds so far from the fossils themselves as it was

their

Exiemal Characters of Fossils* 7S

tbeir oature to be produced in this or that fossil; but, in other respects, the cause is to be attributed entirely to the form of the space which they occu- pied. Lastly, the different external figure of thott which were formed at the same time with the fosnb in and with which they occur, (and to which among particular forms the veimf^ceUular^ and among com- mon forms the interspersed^ frequently belong,) proceeds partly from themselves, and partly from ^ fossils, in and with which they originated.

§•73,

The external form of solid fossils, as already ob« served in 71st. §., is not present in every individual. Nor must we in all cases from a difference of ex- ternal form immediately infer an essential difference in the fossil itself; as it may have arisen, as already shown in the foregoing §., from other cifcumstances as well as from the constitution^ in which case a variety is only produced. But as fossils of the same external form are very rarely met with, tbia character, particularly the crystallization, assists u^ ]oiuch in distinguishing them ; and indeed in com* pany with the two following, which constitute the external appearance, it must often serve us instead of the internal appearance, when this last cannot be observed ; as in the case of crystals which possess their perfect crystallization. The external fomis of solid fossils are distinguished into common

formsj

80 Explication of the

forms f partiadar forms^ regular forms or crysUd* Juatiom, and extraneous fomu»

i 74, 1. Common Forms,

If the natural surface of a solid fossil Neither con* lists of a determinate number of sides^ nor furnishes a resemblance to any known substances in common life, the fossil is said to be of a common form, i. e* of a form in which most fossils occur. It is then also said to be withoui any particular form, of an indeterminate form, amorphous, and (very im- properly) heteromorphous. There are six kinds of common forms, ^&%mussive, interspersed or dissemi'* nated, in angular pieces^ in grains, in plates, and superficiaL

§. 75.

A solid fossil which occurs of an indeterminate form or amorphous, and of nearly equal dimensions, from the size of an hazle nut to the greatest magni* tude, imbedded in and incorporated with another solid fossil, is said to be massive. Solid fossils are most usually found of this external form, several indeed are rarely found otherwise, as Pit-coal^ Steatites, &c. We have massive Native^Silver, massive Galena, massive Copper-Pyrites, Quartz, Limestone, Rock Salt, and many odiers.

§. 76*

External '^Ckarwiers ^ 'Fossils. ^

§.76.

A solid fossil 'which occurs without any particulsr fonii, in little pieces not exceeding the size of a small hazle nut and of nearly equal dimensions, here and there inlaying in and incorporated with another solid fossil) is said to be interspersed, .or dissemi* Tiated. Hence the difference in size constitutes the whole distinction between this and the preceding common form. Interspersed fossils are distinguished tnto^^oarsely interspersed^ where the interspersed parts vary from the size of an hazle nut to that of a pea ; finehf interspersed, from the size of a pea to that of a grain of millet ; minutehf interspersed^ from the size of a grain of millet to one that is still perceptible to the eye. We meet wi£h inter- spersed Natire^Gold, interspersed Native-Silver, also Cinnabar, Martial-tPyrites, Quartz, and maniy ethers.

§. 77, The meaniflg of a fossil in angular pieces is in a gnat .measure explained by the denomination itself We have here however to observe that the pieces must be large, namely) from the. size of an hazle intt to the greatest magnitude, and loose or detached, L e. not imbedded in another fossil. Scarcely any .other difierence therefore exists between this cha- -faoter and massive, than that in the latter the fossil is inhering in« another, in the former, on the eoDtrary, itiis detached. Fossils occuring in angular - pieces jnay be further distinguished into sharp cor »

Q nered

ift EsfffUcation qf the

nered and blunt cornered. Of this form are found Calcedony, Opal from Eibenstock in Saxony, yellow Carnelian, Flint, Bolognian-Stone.

A solid fossil which occurs amorphous, and loose or detached, in small pieces from the size of an hazle nut to one that is still distinguishable by the eye, is said to be in grains. This kind of external ilorm differs from the preceding merely in point of size, and from interspersed particularly in this re« apect, that as the latter occurs inlaying in and incorporated with another fossil, so the former is found detached or only loosely-coherent. It is necessary to guard against confounding this kind of common form with what is called the grain j and granular^ of both which notice will be taken in the explanation and definition of the fracture. Grains may be further distinguished :

I . With respect to the size : into gross grains, from the size of an faazle nut to that of a pea; Lowland-Argillaceous-Iron-Ore, Pisiform Argillace- ous^Irotfltone, are found in gross grains; large gravnsy from the size of a pea to that of hemp seed ; Precious^ Garnet, Magnetic-Iron-Sand ; smaU grains, from the size of hemp-seed to that of millet; the same fossils; minute grains, under which denomination all come, which are smaller than millet-seeds; Platina, Natire-Goid, Tinstone.

2. With

Exietnal Characters of Fossils. 8 3

2. With regard to the figure, into angular grains. Magnetic-iron-sand; arrurtdated grains, Bohemian Garnet, and Pisiform Argillaceous-Iron- stone; flattened grains, Native-Gold, Platina.

3. Accordingly as they inhere in other fossils; into loose, partly, and wholly inhering in other fossils.

§.79.

A solid fossil which occurs in flattened pieces inhering in, or adhering to, another solid fossil, and whose thickness varies from one inch to such a one as the fracture of the fossil will still ad« mit of distinguishing, is said to be in plates. The essential difference between this and the pre* ceding kinds of common forms is, that as in the latter all the three dimensions are nearly equal, so on the contrary in the former the thickness is in comparison with the other considerably smaller. Plates rarely occur regular in fossils, being scarcely ever equally thick in every part. Accordingly we speak of thick and thin plates. We have in plates, Native-Silver, and Vitreous-Silver-Ore.

§.80.

A solid fossil which not possessing any particu- lar form, occurs very thinly laid on the surface of another solid fossil, is said to be superficial This kind of external form is somewhat rare, and peculiar to certain metals only. Superficial is fur- ther distinguished into, thick, thin, and very thin

G 2 superficial.

S4 Explication of the

superficial. We have superficial Native-Siher, Red-Silver-Ore, Vitreous-Silver-Ore,

§.81.

2. Particular Fqrms.

Particular external forms are such as present a greater or less resemblance to substances and their parts, both natural and artificial. They are called particular^ being not usual or common among fossils, like the preceding; and peculiarly apper- taining to other substances. We have the folloir- ing kinds of particular external forms; ist. those which are elongated, as dentiform, filiform^ *ca>- jnlliform, retiform, dendritic or arboriformj sta^^ lactitffomi, coralliformj tubulifonn, fistuliform^ Jiiitescent or arbmtiform, and matraciform ; 2dly. rounded particular forms, as botrtform, globular, tidneyform or reniformy bulbous or noduiary and liquiform; Sdly. flattened particular forms, as spe^ culaVj in lamin^y and pectinated; 4th. impressed particular forms, as cellular , with impressions^ per^ foratedy corrodedy heteromorphoiiSy and vesicular; 5th. and lastly a confused particular form, ai ramose.

§. 82.

Elongated Particular Forms.

I

Dent^orin is that particular form of a soHd fossil which, adhering by the thicker end, is elon- gated toward the other with a curve, and termi- nated

External Characters of Fossils. 8)5.

nated by a point* The deQomination is detiveci^ (roooL its resemblance to teeth, and particularly to iwine*s teeth. This kind of external form is found from the length of a quarter of an inch, and still less, to almost that of a fopt. It is rather rare, and peculiar to certain metals. We have denti- form Native-Silver, dentiform Vitreous-Silver-Ore.

§. 83.

A solid fossil it said to be JUiform which oc« curs in long slender columns resembling wire. It IS also rare, and peculiar to sonve metak oi\ly« lyhea filiform becomes thick at one end and pointed at the other, it passes into .dentiform. We have 61iform Native-Silver from Norway, Aliform Vitreous-Silver-Ore.*

§.84.

A solid fossil which is found in very thin threads, resembling hairs, is said to be capilljforTn, It passes ii^to filiform when the threads acquire a conside- rable thickness. We meet with capilliform Native- Cold, Native-Silver, Martial-Pyrites.

§. 85.

That particular form of a solid fossil which is found in slight coluipns or threads, part of which

run

* Vitreous-Silver-Ore generally possesses the same external form as Native-Silver; probably because it u frequently formed from the latter by the accession of Solphur.

86 Explication of the

run parallel to each other, and are intersected at right angles by others also parallel to each other^ is called retiform. The denomination is taken jfrom a net, to which it bears some resemblance when observed from one side. We have retiform Na- tive-Silver, retiform Native-Copper from Saska in the Bannat,'^ retiform Cobalt, and Sulphurated Nickel from the Himmelsfiirst near Freyberg, and even a kind of retiform Galena.

§.86.

A solid fossil which from a thicker stem sepa-* rates into several more slender, representing branches in a manner, which last also are often- ^ times furnished with smaller shoots, is said to be dendritic^ or arhoriform. Dendritic is either regu- lar, or irregular. The former nearly resembles fir trees, the branches making right angles with the stem, and the shoots right angles with the branches. In the latter the branches are connect- ed with the stem under an acute angle* Both are produced in the slight fissures of solid fossils, and depend solely on their attraction and casual pro- perties. We have regular dendritic Native-Silver from the Himmelsfiirst near Freyberg, and from the Sophia near Wittichen, irregular dendritic Black Haematites from' the Father Abraham near Scheibcnberg, and dendritic Native-Copper.

§. 87. * Vid. Bom Index fMnfium, Brags, 8. r77a» p. soi. a. 7*

JEstemd Characters rfFossSsk Vt

f.87.

CoraUiform is that particular form of a solid fossil which occurs in elongated curved shoots^ resembling corals, the extremities of which am rounded, but differ in this respect from the shoota of stalactitiform as the former are curved in vm* nous directions, several sometimes arising out of each other, and being frequently thicker at the end. We have coralliform Stalactite, Native^Iron, Brown Hoematites.

$. 88.

Stalactitiform is a solid fossil when it consists of several straight shoots of a greater or less length, which are thickest at the port of adherence, be* come slighter toward the extremity, terminate con* vexly, and assume nearly a conical figure. At the shoots of a specimen are always formed in an open space, and this by a succession of drops, and all possess one direction which, seen in the place of their formation, is perpendicular; we may conclude, that gravity was the sole cause of thii figure. From a similitude in formation, arises also the resemblance between stalactitiform and icicles. This kind of external form occurs in stalactiti* form Brown-Iron-stone, Black Hoematites, Stalac* titCj Hepatic Pyrites, Calcedony.

§. 89«

f S ExftkiStam. of dhr

Tuhdiform is that particular external form of a ^lid fossil which consists of straight nearly round columns, possessing^ mostly one direction^ standing beside each other, and adhering at both ends.. Some years since Galena was found in this form, in the Alten Morgenstern, near Freyberg, the co« bimns of which are invested with a brown fine- grained Blende, which was often also minutely crystallised ; the interstices between the columns were also replete with the same substance. We have tubuliform Compact Brown-Iron-stone, Blacky Iron-stone, Hepatic Pyrites.

§. 90.

Fisivliform consists of either single or accugiu- lated columns, being round and internally hollow. ]jt occurs io Martial-Pyrites^ Stalactite.

f. 91.

Fruiescentf or arbustifarm, is that particular ex* Ijernal form of a solid fossil which from a consi- derably thick stem separates into several thick and round branches, terminating globularly, whichy however,, ar^ not much dispersed^ but rather closelj^ crowded together. It occurs sometimes in Com- pact Black-Iron-stone, 'rarely also in Stalactite, aa^ Compact Grey-Ore of Manganese.

Extemat CKaracters of Fossils. 89

• §. 92.

Matracififrm* This rare particulac external ^omi is composed of single, or coalesced, columns ad-* bfiring by the slighter end, and terminating in elongated' globules. Th^ denomination is derived firoia its resembling in figure the matrass of cbe- mists. It ocQUis in Black Hoematites, Brown Hoe* iMUt^, and Compact Grey-Ore of Manganese^

§. 93. Spundei particular forms.

Sotriform. This particular external form of a solid fossil consists in a manner of globes pene- trating into and arising out of each other, and henee ia formed by many greater or smaller glo- balar convexities variously connected with each olher, presenting large sections of small globes* The denoaiinatioii is devived from the resemblande- to a' bimch of grapes. Black-Cobalt-Ore, Grey- Ore of Manganese, . Caloedony, Malachite, Copper- Pyrites, and Striated MartialvPyrites are found in* this particular fotsL

§. 94.

A 8<did fossil which occurs in round pieces is sai^ to be ghhuiar ; of this there are several kinds :

«>

PerfecHy

-/

90 ExpUcatian of the

Perfectly globular or orhicular^ which it fauiid in Pisiform Argillaceoas-lroo-Stone^ White-Cobalt- Ore.

ElUpticalf in elongated round pieces — Quartz and Flint pebbles.

Amydaloid^ arises from the broad flat ellypsi^— QjjartZy Calcareous-Spar, Zeolite, Green-Earth. .

Spheroidal b the round broad compressed form of solid fossils«^Egyptian-Stone, Carnelian.

Imperfectly globular is a soli4 fossil which ap- 'preaches nearly to the form of a globe, but diflers

«

from it in possessing indeterminate and sometimes casual inequalities. Imperfectly globular are Cal- cedony, Agate, Martial-Pyrites.

$. 95.

By kidney form^ or reniform, is understood that particular external form of a solid fossil, which consists of several larger or smaller globular elera* tions, each of which is composed either of one elevation, or of several smaller. It appears like- wise to owe its origin to a succession of drops, and hence passes into stalactitiform. The deno- mination is derived from its resemblance to kidneys^' particularly to those of cakes. It may be further distinguished into large and small reniform. We ' have reniform Red Hoematites, Black Hoematites^ Martial-Pyrites, Native-Arsenic, Malachite, Calce* dony.

§.96*

External Characters of Fossils. 91

§. 96.

Btdbous or nodular y is that particular form of a solid fossil, which consists of several rather irre- gularly globular elevations, between which in ge* neral the same kind of depressions occurs. We have nodular Flint, Martial-Pyrites.

§. 97.

Liquiform is that particular form of a solid fossil wfiich consists of one or more flat round ele- vations, detached from, or connected with, each other, generally depressed in the middle, and oc- casionally accompanied by some minute globules. The denomination is derived from the resemblance which this particular form bears to that of metals which, being in a state of liquidity, present a globular appearance with a small depression in the centre. Liquiform occurs in Galena from the Altea grunen Zweig, Erbisdorf, near Freyberg, and in the same substance from the Himlisch Heer.

Flattened Particular Fortns.

$.98.

Specular is a solid fossil which presents on one side an almost even polished surface. This sur- face, being smooth, generally possesses a consi- derable degree of lustre, and reflecting the rays ^ light, is called specular, and in so far is a com- plex

Mt Explicaiim of the.

plex character. It always arises in the walls or sides oC veins, and is merely a smooth separation of the vein from the rock. We have specular— « Compact Galena, Martial-Pyrites, Compact Red- Iron-stope.

§. 99.

In laminae is a solid fossil which consists of vetj tbin plates, being somietimes straight, sometimes curvated, and inhering in another solid fossil, or merely adhering to it. This external form is rare and peculiar to some metals only. We have in bminae — NativerGold, Native-Silver, Vitreous-Sil-* ▼er-Ore:

§. 100.

Pectinated. This is formed by tables which are disposed beside, and upon, each other; presenting die appearance of hair parted by the comb. 1%. occurs only in Quartz brought from Shemnitz.

§. 101.

Impressed Particular Forms.

A solid fossil is cellular which consists, in a manner, entirely of tables crossing and intersect- ing each other,* thus forming cells. There are several kinds of cellular: as,.

Hexahedral ceUidar^ which may probab^ arise from the fossi} insinuating itself into the rifts of su^h fossils as break in cufaes or rhombs, wbichi

in

External Characters of TossUs. 9S

Iq lime becoming decomposed, the hes^ahedral crib vetnain« Of this kind we hare cellular partial- Pyrites.

Polyhedral celbdar. This abo consists of angular and straight-sided celb, but which are in other respects indeterminate. Cellular Quartz, oellular Calcareons-Spar.

Parallel round cellular ^ which bears the grebt* est resemblance to a honeycomb. Of this "kind we have Quartz, and rarely Sparry-Iron-Ore.

Spongiforrfi ceUular. The cells of this particu- lar external form are more irregular than the for- mer, being with respect to relative position ncM; parallel, but confusedly thrown one among ano- ther. It occurs in Quartz.

Indeterminate round cellular j in which, with respect to form and position, almost each cell dif- fers from the other. Hepatic Pyrites, and Brown- Iron-stone are found in this particular form.

Double cellular^ in which large cells comprise several smaller, as in Quartz and Hepatic Pyrites.

Veirty cellular, in which the cells are replete with other fossils, as in White-Cobalt-Ore, » in which the interstices are filled with Manganese.

§. 102.

With impressions. This form may prbbably arise from the deposition of a soft mass upon a harder !'(particiilarly on crystallizations), becoming gr»- dually indurated. We have,

Cubical

§4 Explicaiwn of the

Cubical impressions J (commonly of Fluorspar,) which occur in Quartz, Martia1*Pyrites, Hepatic Pyrites, Hornstone, and Calcedony.

Hexahedrdl pyramidal^ in Homstone, and Quartz. ' Conicatj in Native-Arsenic, and Quartz.

Prismatic and tabular j in Quartz, and some Sidero-calcites.

Globular, in Vitreous-Silver-Ore.

§. 103. -

A solid fossil is said to be perforated, when traversed with round, deep, and narrow holes. Of this kind is Lowland-Argillaceous-Iron-Ore. This particular form may have originated in roots, which penetrated the fossil when soft, but decayed after the latter had become indurated.

§. 104.

A solid fossil is said to be corroded, when en- tirely traversed with small cavities and interstices. The denomination is taken from worm-eaten wood, which* it much resembles. We have corroded Vitreous-Silver-Ore, Galena, Quartz.

§. 105.

I/eteromorphous is that particular external form of a solid fossil, which consists of larger or smaller indeterminate elevations and depressions, the for- mer of which are sometimes blunt, sometimes sharp. Bearing some resemblance to the excres- cences

External Characters of Fossils. 95

cences of plants and animals, the denomination haa been thence derived. We hare beteromorphoua Native-Iron, heteromorpbous LowIand-ArgiUaceous- IroD-Ore^ Swampy-Iron-Ore^ Native-Arsenic. -

§. 106.

A soBd fossil is said to be vesictdar wbich possesses

small, more or less round, cavities, as well on tbe

«

exterior as in tbe interior. It is not essential tbat these cavities be connected one with another. It occurs in Lavas, Pumicestones, Earthy-Scoria, some Limestones, Basalt, &c.

Confused particular form.

$• 107..

Ramose is that particular external form of a solid fossil which consists of several crooked branches, which neither arise from a common stem, nor possess a proportionate thickness ; but are formed irregularly, growing one among another and several out of each other, and curved in different di- rections ; are sometimes thicker at the extemity, sometimes at tbe part by which they adhere, and have several sharp sides and edges. When the branches become smaller, shorter, and thicker, it passes into heteromorpbous. Of thi^ form is Native- Iron from Siberia, sometimes also Native-Copper, but very rarely Vitreous-Silver-Ore.

§. 10^.

$6 JSjtrpUcaiioH if ike

§. 108.

. 5. Regular forms, or Crystallzaton^a

Tbe third kind of external forms, namely regular forms or crysiaUizdtions, are those natural surfaces of solid fossils which consist of a determinate ntiai^ •ber of planes associated in a determinate jnanaen

§. 109.

Hitherto much neglect has be^i shewn in the determination of crystallizations : the greater paM having been very imperfectly defined by tbe num-» ber of their planes or solid angles, and many haying been indiscriminately called polyedral from the difEcuIty which was experienced in ascertaining their exact form ; hence any form might be ima^ ^ined which should be thought proper. Howevet, as crystallizations by reason of their regularity aie not only capable of a more accurate definition than other external forms, but also in particular requnne a good definition from the great difference which subsists between them ; it is certainly necessary that «t more careful attention should be bestowed on the subject.

§. 110.

In defining crystallizations we have four things

to consider ; the essential fuality of tbe crystals^

their form, aggregation j and magnitude,

f. UK

External Characters of FossUs. SI

1. The essential quality of crystals.*

§. 111.

By the essential quality of crystals is understood that distinction which refers to the mode of theit formation ; as having taken place, either in a man- ner conformable to the laws of nature, or untiatu- rally and irregularly. 'Accordingly crystals are di»- tinguished into genuine j and spurious, or qfter^ . crystals. The former are by far the most frequent in nature. The latter, by reason of their scarcity, are the more highly valued in the cabinets of the curious.

These appear to be produced in two ways: 1st, when genuine crystals become incrusted with a foreign substance, in course of time decay, and leave the incrustation exhibiting their form ; 2d, when genuine crystals which inhered in another fossil, having decayed, the spaces so left became occupied by another fossil of a later formation, which afterward separating from the impressed mass exhibits the form of the ancient genuine crys- tals. The former case is an incrustation of genuine crystals ; the latter is a repletion of the space formerly occupied by genuine crystals. Both cases frequently occur in Calcareous and Fluor-Spars. Thus we have Flint as the spurious, or after-crys- tal of the double trihedral pyramid of Calcareous-

H Spar;

5S JSxpticatiM of the

Spar; Calamine- from Derbyshire as.t&e spurious crystal of the hexabedral prism of Calcareeus-Spar, aeumioated by three planes; and Quartz as the- spurioiM crystak of the cube^ and of the octahe- dron^ of Fluor-Spar.

Serious crystals are partioukffy disttngiiiihed kgr the following characters :

They are always holbsat, or at least possess w anall aperture-; their sur&ce- is rough, or. drusj/^ iMit never sihooth ; their solid angles, and edges, are never sharp or well defined. ; they are- not, like genuine crystals, connected by transitioDs witb other crystals of the same ccmstituent principles, b«t rather from their lig«are generally lead to the cfis- covery of the fossil to- whicb they casually owed,

Adr fevm.

*

3. The form of crystals*

f. 1 J2.

This ia certainly the most eminent property of crystals, since it commonly serves as a distinguish^ ing character of those fossib in which it occurs. The form of crystals is> composed of* the following parts : planes, the definition of which may be found in geometry ; ad^^5,— formed by the junction of two planes under determinate angles, whose extremec therefore are lines ; and solid angles formed by tbm conjuDctioa of three or more planes in quc poiafw

T#

External Characiers ^ FossiU. &•

To determine the form of Crystals it is first ne- cessary to define their primary or fundamental forms j^ and then the several variations at mod^ cations to which these are subject.

Primary forms of aystatt,

$. 113.

By the primary forms of crystals we Understand (heir most simple forms (which consist of only one or at most of two kinds of planes, namely lateral planes and extreme planes :J and which, though they exisX, in crystals possessing a Variety of planes^ may yet be easily distinguished by conceiving those planeft which lie nearest to the center of the crystal, and which are generally the largest^ to be extended on all sides until they conjoin.

Parts of primary forms^

- $. 114.

The parts, of which thd primary fotms of crys* tals are composed, are ; Planes^ which are dis* tinguished into—

H ^ 1 . Lateral*

* It it to be understood that. In assuming eertain primary forms ti crystab, and supposing these to undergo peculiar modifications, Mr^ Werner only proposes to dacrUt crystals, and not to indicate the course pursued by nature in their formation. He employs a j;»ecnliar descriptlTc language to convey ideas of the various forms of crystab, and not to explain the order of their construction. Oa •Ut htttr subject, c<HMult Abb^ Hafiy's excellent Trait^ de Mine* fslogiey vid. Tom. L p. 19. ct scq. Theorie de la Structure dcs Cris* taux. Tft.

100 ExpUcatum of ihi

t. Lateral planes ; which considered as parte of the surface of the body are of the greatest extent^ but form the confines of the body toward its smalU est extent.

2. Extreme planes ; which are of the smallest extent^ and form the confines of the body toward its greatest extent.

EdgeSy which also differ, being —

1*. Lateral edges ; which are formed either by the junction of lateral planes with extreme planes;, as in the, table; or by the junction of lateral planes one with another, a» in the prism and py* ramid.

2k Extreme edges ; which arise-— either from the junction of ^extreme planes one with' another, as in the table ; or from the junction of lateral phines with extreme planes, as in the prism and pyramid.

Solid angles, which have been already defined*

Kinds of primary forms^

There are seten iinds of primary forms, zuA tiiese are ; the icosahedron, the dodecahedron, the hexahedron, the prism, the pyramid, the table, and the lens*

The icosahedron, as the first, is that primary fi^rm which consists of twenty equi-lat^al triamgular

planes^

. 1

t

1

External Characters of Fossils. , 101

planes, assotiated under equal angles. It occurs in Martial-Pyrites and White-Cobak-Ore, very rardy however.

i. 117. ^

The dodecahedron k that primary forna, which is composed of twelve regular pentangular planes^ associated under equal obtuse angles^ ^ It must not be confounded with an hexabedral pris« matic crystallization y which occurs in Calcareous* Sp^r^ and which very much resembles it. The dodecahedron is found ijo Martial-Pyrites, and also in Whijte-Cph^-Orp from Tunaberg in Sweden.

f 118.

The hexahedron (in which are included the cube and the rhomb) is that primary form wJMch consists «f six quadrilateral planes. || This kind of crystalli- sation occurs very frequently in the mineral king- doo). T^us we t^ave cubical crystallized Cinnabar^

cubical

^ ▼. Lumad Syftema Katnrc, Holm. 176S, Tom. HI. Tab, L «mI XL hg. 3a

Abbe Haiiy obsenrct that the icosahedron and dofleca^ednnij described above bj Mr. Werner as the regular solids of geometry, canofOt eiist in the mineral kingdom consistently wtth the laws of crystallization. Acosrdiag^ to him, the icosahedron which occurs consists of eight equi-Iateral and twelve isosceles triang;les ; and the dodecahedron varies in the angles under which its plknes are associ- atcd. ^d. Traite de Mineralogie Tom. L p. to, 41J, and 4%%-^ Mnd Tom. IV. p. 7a and 79.

Vid. also the annexed PI. I. fig. i, and 4. tr.

t Vid. Linnari Systema Nature, Tom. lit Tab. L and IL fig. zz.

I Vid. Linnaei, Tab. I. and II. fig. 18, 19, ao, and a9.

Vid. also the annexed PL I. fig. Zand '4. tr.

109 jSxplicaiUm of the

cubical Vitreous-Silver-Ore, Comeous-Silver-Ore, Galena, Specular Iron-Ore, Martial-Pyrites, Rock-» ^t, Fluor-Spar, and rhomboidal crystallized Cal* careous-Spar^ Sparry-Iron-Ore, Sidero-calcite, |Uk) many others^

The prism is that primary form which connsta ^f an indeterminate number of quadrangular late* ral planes possessing one direction, and all termi- nating in two extreme planes, each of which has ^ many sides as the crystallization possesses late«. ral planes.* This is the most common crystalIi-> zation occurring among fossils. We have pris-r inatic Green, White, Black, and Red-Lead-Orea, Tinstone crystals, Arsenical-Pyrites, Rock-crystal, Quilrtz, Topaz, Shorl, and many others.

§. 12Q.

The pyramid is that primary form which con^ fists of an indeterminate number of triangular la^ teral {daxies converging to a point, and of a base possessing as many sides as the crystallization has lateral planes, f Next to the prismatic this is the

mosi

• V. Linnsi. Tab. I. H. dc III. Fig. x, 4« 5f ^* h S> 9> Il|

?»t I4» 3a» ZZ^ ^ 34. Vid. also the umexed PL I. Fig. 5, 6, 7, %% ^ 9* T^

flbld. Tab. L U. & IIL Fig. 3» 13, dj, %At ^5* ^^9 dii 37^ Vid. abo the aimMc4 PL ^ ^%- IO9 ih Ih ih ^^ ^i* ^^ I7i ft z8. Tk.

Uxfertud Ckarnoters t^ Fossils. 163

alMt frequent crystdltzatton occuttiiig aittong fob* eils. We have pyramidal Light Red^iiltei-Orey Grey->Copper-Ote, Quartz^ Calcareous-Spar, Am^ tkyst, PrasiuBU

The labk is tbat primary form which is com' * {KMed of two parallel later^d planes, being tery iarge in comparison with the other planes; and <of an indeterminate number of little, narrew, and sometimes almost imperceptible, exlveme pktneSf nrhich are connected both with the lateral planes and with one another.* Hehce the <nrjstftls of tUs 3und are of a slight thickness, of a great length, and of a great breadth, which always much ex* <{eeds tbe thickness but nearer reaches tbo length. Tabular crystals ate rather scavce. We have ta* 4>ular orystallisGed Specular-kon-^Ore, jgrey Miea, dalcaveottb-Spar^ JBar^nelenite, '

5. 122-

The Jens is that primary lorfti wUdb tonaifb of two lateral planes oaly, difief ing accordingly as ^he lateral planes are differently curred. Hence there are two kinds, the 'common lens composed of two convex iateral planes ;* and the sdl(fdnn cw$isting of one convex and one concave lateral

pi.

• V. UanxL Tab. t tl 8c. III. Fig. 17, & %f. '

tltti tht attoetcd PI. I; Rg* 19^ ftOj st, li as. Tiu

t yiL the umexed PL L Fig. a3i ^ 04* '^^

10# Eaplication ef the

, plane, bearing some resemblance to a saddle whence its name. Both common and selliform lenticular crystals occur in Sparry- Iron-Ore, Sidero-calcitr^ and Calcareous-Spar.

Differences in each kind of primary form.

These primary forms, whether perfect or vari- ously modified, differ further from each other m respect to simplidii/f position, the number and size ' of the planesy the angles under which these are associated, the direction of the planes, and the ftdness of the crystals.,

«

§. 124.

With respect to simplicity primary forms are ^ther simple GC douile ; This distinction, however, is confined to the pyramid, as the other six kinds of primary forms occur simple only. In the dou-» hie pyramid two cases occur with respect to the apposition of the lateral planes: in the one, the lateral planes of the one pyramid are set directly on the lateral planes of the other, which is the general case, or obliquely, as in double hexahedral pyramidal Calcareous-Spar; in the other, the late- ral planes of the one pyramid are set on the late-' Wei edges of the other, as in double trihedral py« ramidal Calcareous-Spar. We have simple pyra- midal Light Red-Silver-Ore, Gi:ey- Copper-Ore, Qmrt^y Amethyst, and double pyramidal Vitreous-^

Silver^

External Characters of Fossils. V0$

Siher-Ore, Galena, TinstOpe crystals, Rock crys- tal, Calcareous-Spar, Ruby, Diamond.

§. 125.

The difference in position is also pecujdar to the pyramid, and confined to the simple pyramid; -which, accordingly as ^t is found adhering to siikv ther fossil by the base or by the apex, is said to stand erect or inverted. The former case i9 the most common, the latter having occurred only in a few specimens of simple hexahedra^ pjt ramidal crystals of Calcareoqs-Spar,

§: 126.

> The number of planes in the primary form is

in some kinds determinate^ in others variable. Jt

is determinate iti the icosahedron, dodecahedron,

hexahedron, and lens; of which the first cannot

possess more than twenty planes, the second than

twelve, the third than six, and the fourth than two«

It is variable in the other kinds. In the prism and

pyramid the lateral planes vary, and in the table the

extreme planes vary. Thns the prism occurs ;

1. With three lateral planes in the trihedral prism of Shorl, Tourmaline, a)id Cinnabar.

2. With four lateral planes in the tetrahedral prism of ArsenicaUPyrites, Jargon, and Tinstone.

3. With six lateral planes in the hexahedral prism of Gre^i^Lead-Ore, Calcareous-Spar, and Park Red-SilVer-Ore;

4; With

Expiicathn of the

. 4* Widi df^ht iatei;ad plane0 in the MtoheSral prism of Topaz, Vitveotts^Silwr-Ofe, and Dark Rfid-Silver-Ore.

The pyramid occurs,

1. With three lateral pitaes in the simple tra« hedral pyramid of Grey-Copper-Ore, and Coppef- l^riees; and in the double trihedral pyrafnid of )dah:areo«»-Spar, and Siderocalcite.

2. With four lateral planes in the double tetra* iiedral pyramid of Ruby, Galena, and Vitreous- SUrer-Ore*

3. With six lateral planes in the simple hexa« bedral pyramid of Light Red*SiIver-Orc and Quartz, and in the double hexahedral pyramid of Calcare* ous-Spar, and Striated lled-Cobalt-Ore.

4. With eight lateral planes in l^e double octo- bedral pyramid of Garnet, Zeolite, and Native* Gold.*

The table^ though it possess iNily two hrge lateral planes, is yet variable in its number of ex- treme planes, which are always as maay as the aides of the lateral planes.

The

* This erfUilf which is a low, verj acute, double «ctohedral pyramid, the lateral planes of the one set on the lateral planes of the other-^is, moreovefi obtusely acuminated at both sumnuti by four planes, set on the alternate lateral ed^es. Hence it con* nsts of twenty-four trapezoidal planes associated in such a man« Iter that, let the ctystal be obserTcd on wliat side it may, a particular association of four planes presents jlielf, the point tf which may be considered cither as the superior or inferior 5um« «ut af Ule crystal

Extenud Characters of Fosnb, 101

The table occurs,

J . With four extreme planes in the quadragonal table of Baroselenite, YeHow-Lead»Ore, and Ca- lamine.

2. With six extreme planes in the hexagonal table of Mica, Antimoniated-Sil^er-Orey and Ba^ roselenite.

3. With eight extreme planes in the octagobal table of Yellow-Lead-Ore, Apatite, and Baroie« lenite.

The prism and pyramid may possess a greatat number of lateral planes, and the table, of ex« tfeme planes ; but in the former the number of la;- terai planes nerer falls below three, and in thci latter the number of extreme planes never beknr four;* and in the one or the other, the number of lateral planes or of extreme planes rarely ex«» eeeds twelve, f

On this subject I will only further remark lhat| without paying any particular attention to the equa^ lity of angles, the simple trihedral pyramid is called tetrahedron^ and the double tetrahedral pyramid pct^hedron^

5. irt

* To this there teems to be an etception In the case of drey* OoppeP4>te. Vid its dcwnptioa in the i/tii Chap. Tfk.

t It u worthy of remark that among the polyedral erystalll* Mtioas of the prism, pyramid^ and table, not one of the twa former has hitherto been found with five or seven lateral plaae% or of the latter with ^Jt or.ierca extreme . plaaeti

}

ItWI Explicdtian of ike

§. 127.

With r^ard to the size of the planes in relation

to each other, rarely any thing very determinate

occurs. The variation in this respect, bowerer, is

^iefly observable in the lateral planes of the prism

and pyramid, and in the extreme planes of the

table. We have here to observe the lengthy and

the breadth, of the planes* In relation to the bread^h^

the planes are equal or unequal, and in the latter

case tndcterminate or determinate. Indeterminately^

unequal are in general the lateral planes of thci

hexahedral prism of Rock-crystal. Determinately--

uneqiial are the lateral planes of prismatic White-

LeadTOre firom La Croix, and of hexahedral pris*

Viatic Calcareous-Spar from Andreasberg, being

4iUematehf broad and narrow : determinately-une«-

qual are also the lateral planes of broad prismatic

^ock-crystaly and of prismatic Gypsum in generalj

in both which equal broad or narrow planes aro

opposed to each other*

$. 128.

The angles, under which the planes are associated, are the following :

1. The angles of the lateral edges, the idea of which is already conveyed in the definition of the lateral edges. In relation to these, the planes of crystals are said to be associated either equi-angU" larly, rect-angtdarfy, oblique-angularly, or unequi- angularly.

In

External Characters of Fossils. 109

In the icosahedron the planes are always associ- ated equiangularly, as may be seen in the tcosa- faedral crystals of Martial-Pyrites.*

In the regular dodecahedron the planes are always equi-angularly associated ; in the irregular, on the contrary, the planes are uneqiri-angularly associated. Examples occur in Martial-Pyrites.*

In the hexahedron «the planes are sometimes^ rect-angtdarly, sometimes oblique-angularly^ associ- ated ; the former case occurs in cubical Fluor* Spar, Calcareous-Spar, and Vitreous-Silver-Ore ) the latter in rhombondal Calcareous-Spar, Sidero- ealcite, and Felspar.

In the trihedral prism the lateral planes are generally equi-angularly associated, as in the tri« bedral prism of Shorl, Tourmaline, and Cinnabar, In the tetrahedral prism, on the contrary, the lateral planes are associated either rect-angularly, as ia the rect-angular tetrahedral prism of Garnet, and Jargon ; or oblique-angularly, as in the oblique angular tetrahedral prism of Baroselenite, and Arsenical-Pyrites. The lateral planes of the hexa- hedral prism occur partly equi-angularly, and partly unequi-angularly, associated ; the former in the eqai-ang^lar hexahedral prism of Calcareous-Spar, Emerald, and Green-Lead-Ore ; the latter in the unequi-angular hexahedral prism of Rock-crystal, and Baroselenite. The octohedral prism occurs

rarely,

f Vid. the note to the 1x7 $. tiu

116 ' ExpHcaiion ef the

rarely^ and eitfaer with eqai-atigulatiy or ttnequU angulariy associated lateral planes % the former in the equi-angular octohedral prism of Dark Red^ Silver-Ore; the latter in the nnequi'-angQlar octo- hedral prism of Topaz.

The trihedral pyramid occurs commonly with equi-angularly associated lateral planes, as in the tri« bedral pyramid of Grey ^Copper-Ore, and Diamond, The tetrah^ral pyramid is found both with equi* angularly and obltque-angulariy associated lateral planes j the former ir^ the double rectangular tetra^ hedral pyramids, or octahedra, of the Diamond, Magnetic-Ironstone, and Red-Copper-Ore ; the lat- ter in the^ oUique-anguIar tetrahedral pyramid of Natural-Sulphur. Lastly, hexahedral and octohe- dral pyramids are usually found with equi-aogularly associated lateral planes; the former in Sapphire^ and Rock crystal ; the latter in Garnet, Native* Gold, and Martial-Pyrites.

With respect to the table one case only occurs in which the angles of the lateral edges are un-* equal ; as in the hexagonal Table of Specular-Iron- Ore, in which the extreme planes are alternately obliquely applied to the lateral planes.

2. The angles of the extreme edges. In prisms the angles of the extreme edges are generally rect* MngloTy the extreme planes bring rectangularly ap- plied to the lateral planes. Exceptions, in which the angles of the extreme edges are oblique'CngulaTf occur in the tetrahedral prism of Felspar, and Red<*

Lead-

External Characiers ^ Fas^^ ix i

I^ead-Ore^ with parallel obliquely sq;iplied estreae planes* la pyramids the angles of the extreme edges are getierally equal. la tables, on the other band, the same case occurs with respect to the angles of the extreme edges, as in prisms with respect to the angles of the lateral edges, Tbu» we have quadragonal tables ia which' the extreme plances are sometimes rectangularly, sometimes eblique-angularly, associated ; as in the rectangular quadragonal table of Baroselenite and Micaceous* Uranitic-Ore, the oblique-angular quadragonal table of Baroselenite and Prehnite : and hexagonal tabled in which the extreme planes are sometimes equi-angularly, sometimes unequiangularly, associ- ated; as in the equi-angular hexagonal table of Mica, and Antimoniated-Silver-Ore, the unequii- , angular hexagonal table of Prehnite.

3. The angles of the summit or apex^ which are confined to the pyramid, are distinguished into*-^ very 0btuse, obtuse, rather obtuse, rectangular, rather accute, acute, and very acute. The extremes of obtuse-angular summits are found in the double trihedral pyramid of Calcareous-Spar, in the yery rare double trihedral pyramid of Tourmaline, and in the double trihedral pyramid of the Bra&ilian Pianood ;* and acute-angular is the summit of

the

a Hut crystal it 9 yery obtuie double trihedral pyramid, with

i^GpdricaUy-conyci Uteral plane* ; the angles of the conunoo base

very

113 Explication of the

the double he^hedral pyramid of Calcareous-Spar^ 9nd very acute are the summits of the double hexa- hedral pyramid of Sapphire, and of the double tetra- hedral pyramid of Arsenical-Pyrites.

J. 129.

The directum of the planes b either straight or curvated. Straight planes are even surfaces, and by .far the most common. Curvated planes are much more rare, and are distinguished —

1. In relation to the position of the curvature, into inwardly curvated or concave, and outwardly curvated or convex :

2. In relation to xhefonn of the curvature, as re- sembling a spherical, cjOindrical, or conical section^ into spherical, cylindrical, and conical planes.

Spherically-convex planes occur in cubical Wbite- Cobalt-Ore, cubical Fluor-Spar, and cubical Mar- tial*Pyrites ; spherically-concave in cubical Galena^ cubical Martial Pyrites, and cubical Fluor-Spar. Cylindrically-convex planes are found in theBrasillaa Diamond, trihediral prismatic Shorl and Tourmaline ; cylindrically concave in hexahedral pyramidal Cat* careous-Spar, in rhomboidal Siderocalcite, and ia tetrahedral prismatic Arsenical-Pyrites. Conically- convex planes occur in trihedral pyramidal Brown and Black Blende, and conically-concave indis- tinctly in Galena.

§. 130.

very obtusely acuminated by four smaU planes, wnich are set on the lateral planets and both the summits raonded.

External Characters of Fossils. 113

. §. 130.

With respect to fulness^ crystals are perfect or full, hMow at the extremity ^ or the cavity, runs through the wh<de crystaL Genuine crystals are commonly found perfect or full, Tfith some few ^Eceptions which occur hollow. Thus we have crystals of Calcareous-Spar, Green-Lead-Ore, cu- bical Comeous-Silver-Ore, hexahedral prismatic Dark Red-Silver-Ore, which are hollow at the extremity ; and prismatic Beryll, in which the-ca- ▼ity runs 'sometimes parallel to the direction of the Jateral planes through the whole crystal. *>

m

Modifications of the primary forms.

§. 131.

. The variations or modifications of the priodary Ibrms, by which they sometimes lose their extreme l^nes, sometimes their peculiar edges, and solid angles, may be conceived as caused by truncation, kvelling, and acuminatum. The planes which arise from these variations mity be easily distinguished from the planes of the primary form, being more ^distant from the center of the crystallization, and ki general smaller, than tlie latter.

The Truncation.

§. 132.

A crystal is said to be truncated when some or all its peculiar solid angles, or ,edges^ appear cut

• I off.

.11^ Sxplieaiim ^ the

dffy in a manner ; a plane occurring where a point er edge should be.* Hence truncation consists of fingJe planes only.

We bnv^ here to consider:

X. TWparU oi the truncation as eonsisting ti 4k^ jiM0^ edges, apd imgles, of tnincalioo. .

jl« Tbe ieUrmmatwn of the troncattoo as m-

{€j The^ tiiuation of the truncation, which oo- €Ws either at tbe angles, or edges, of tbe prinarjr fprm.

{^J The magnUuie of tbe truncatioo, which in relation to the planes of tbe primarj form is smaU^ or large; in the former case the angles or edges of crystals are said to be slightly, in tbe latter deephf, truncated.

(c) The dj9{p/iai<«!pn cf the truncatton, which is tidier iirect, (the most usual case,) or ebUfue, L e, let on one plane in particular. Inslamces of ohf lique truncation occur in the angles of the common base of tbe doable trihedral pyramid of Specular* ^ Iron»Ore, and in Uie edges of cubical Martial-Py* rites.

fdj Th^ direction of the taruncation, l^e trun* eating plane being either an even surface, (which is generally the case,) or curvated.

Truncation is met with in cubical, prismatic, pyramidal, and tabular crystals; but chiefly in

the

• Vid. the Annexed PI L fjg, s/, aft, S7, at, 19, 30, 31, It 3a, Ts,

External Characters of Fossils. 115

the three former. Among the truncated crystak of fossils may be distinguished^ cubical Galena, with truncated angles ; tetrahedral prismatic Tin« stone crystals, with truncated edg^ ; double tetra- hedral pyramidal Tinstone crystals, with truncated edges; double tetrahedral pyramidal Galena, with truncated angles; octi^onal tabular Baroselenite^- with slightly truncated lateral edges.

The Bevelling.

§. 133.

A crystal is said to he bevelled when some or all its edges, extreme planes, or solid aoglesi are so altered as to present in the altered part two smaller converging planes, terminating in an edge.* This is the rarest kind of variation with whioh crystallizations are found.

We have here to observe:

1. The parts of the bevelling as consisting of the bevelling planes ; of the bevelling edges, (distin*- guished into the proper bevelling edge formed by the conjunction of the bevelling planes; and the bevelling edges formed by the junction of the be- yelling planes with the lateral planes of the pri- mary form) ; and of the bevelling angles.

2. The determination of the bevelling as relat- ing to —

1 2 raj The

• Vid. PL I. fig. 33» 34> $S* 3^> & H- a Fig. j;, at 39* ^ 4a Ti.

116 Explication of the

(a) The situation of the bevelling, which occurs either at the extreme planes, at the edges, or the solid angles, of the primary form. The bevelling of the extreme planes is confined to the prism and table ; of the edges, it occurs in the hexahedron, prism, pyramid, and table ; the bevelling of the solid angles is very rare.

(b) Tlje magnitude of the bevelling planes, in relation to those of the primary form, which are small, or great ; in the former case, the extreme planes, edges, or angles of crystals are said to be slightly f in the latter deeply y bevelled,

(c) The angle under which the bevelling planes 'Conjoin, which is acute, rectangular, or obtyse,

and in relation to which crystals are said to be acutely y rectangularh/, or obttisely, bevelled.

(d) The continuation ,oi the bevelling as being uninterrupted or interrupted^ and this once or twice interrupted. We have acute-angular double trihe- dral pyramidal Calcareous-Spar, with the lateral edges once interruptedly bevelled ; and oblique* at)giilar quadragonal tabular Barbselenite, with the obtuse extrertje edges twice interrupted!)' bevelled.

(ej The application of the bevelling itself 3& be- ing direct J (the most usual case,) or oblique, which occurs in hexahedral prismatic BasaItic*Hornblende; and of the bevelling planes, as being set on the lateral planes, or ou the lateral edges^ of the pri- mary form.

V This

External Characters of Fcssib. 117

This, kind of modification of the primary form is fpund in tetrahedral prismatic ArsenicaUPyrites^ with the extreme planes very obtusely bevelled ; in rectangular quadragonal tabular Baroselenite, with acutely bevelled extreme planes ; in cubical Fluorspar, with bevelled edges; in trihedral pris* raatic Tourmaline, with the lateral edges obtusely bevelled ^ in trihedral pyramidal Grey-Copper-Ore^ with bevelled edges ; in oblique-angular quadrago^ nal tabular Baroselenite, with the obtuse extreme edges bevelled ; in tetrahedral prismatic Jargon and Tinstone with bevelled angles; in double te-. trahedral pyramidal Tungsten, with the angles of the common base slightly bevelled ; and in dou- ble tetrahedral pyramidal Martial-Pyrites, with all the angles bevelled.

The Acumination. §. 134.

Acumination is that kind of modification of the . primary form in which a crystal loses some or all its angles, or extreme planes, presenting in their stead, at the altered part, three or more planes converging together.* This kind of variation is the . most common which is found in crystals.

We have here to consider;

i. The parts of the acumination as consisting of the acuminating planes ; of the edges of acumina- tion^

♦ Vid. PI a Tig. 41, 4S, 43, 45, 46, 47, 48, 49. * SO. Tt.

118 Erplication of^ the

tion, (which are distinguished into — the proper cfdges of acutnination formed by the junction of the acuminating planes with each other; the ^jr- freme edge of acuminatlon which sometimes occurs ihstead of a point; and the edges of acumination formed by the junction of the acuminating planes with the lateral planes of the primary form ;) and df the angles of acumination.

2. The determhuLtion of the acumination as re- lating to —

(a,). The situation of the acuminating planes, Tvhich occur either at the solid angles^ or at the extreme planes, of the primary form* The acu- mination of the prism is always situated at the ex- treme plapes, of the cube usually at the angles, and of the pyramid generally at the summit. Acu- minations of the cube occur in cubical Martial-Py- rites, whose angles are acuminated by three planes set on the lateral edges; and in cubical Fluorspar, Zeolite, and Martial-Pyrites, with the angles aeu- minated by three planes set on the lateral planes. Acuminations of the pjrramid at the angles occur in the double trihedral pyramid of the Diamond as afaneady described ; and in the trihedral pyramid of Grey-Copper-Ore, with the angles acuminated by three planes.

fh.) The planes themselves; in which we hate to observe,

«

1* Their number, the acuminating planes being either equal to or fewer than those of the primary

form

Extemd CHataetisrs qf Fossib. M

ferin witb which they tute associated; tfon by thf ee planet cecum in the hetabedral priMtl of Caltareoti^-'Spar and Gatnet, and in the tribes dral prism of Tourmaline; by four planes, m ihd fetrahedral prism of Jatgon and Hyatioth, in the oatobedral prion of Topaz^ and in the dombte oe^ fohedral pyramid of Garnet, Leuciie, and NMiM GoM ; by she planes, in the hexahedral prism of CiA^ caieouft-Spar and Rock-crystal, and in the sitoplift hmcahedral pyramid bf Light R«M}-8llvei^0re ; by «gfat planes, in tetvahedrai pri^DOMtc Tinstone ei^ tak from Cevnwail, i« tetnibedral prisnatie TopiMS^ and is octobedrat prisiMtic Darl^ Radt-Sllf«r-Or«i^

3. Their relatrte size, nrhieK is ejfM or ufiBftitk \m Qimrtfl and Rock-crystal* the planecf o^ acumi^ aation are generally iAdeteffmlnfttely nne^ual, adtf in Batoseleiiite determinately tete^aU

S. Thei^ /ofm wMch is determinate oif iHdeUf^ minate. Determinate acuminating planer ^eui^ m prfaraotie CAs^teotk^Spanf, Hyatinth, kc.^ itad with respect to the form, they are sobVetime^ rfiombs, someum^s triangles, and often polygon^; Indetenninate aeuminrntsng pbi^es afe found in iM crystals of JargO^ and Wolfram.

4< Their applieation, the acutninating plaYM be-'* ing set either t/tit the lateral |^nes, or on the latMA edges, of the primary form, and in both cases either directly or obliquely. This is an essential difference in many crystals. Both Jargon and Hy* acinth occur in tetrahedral prisms acuminated by

four

ISO StrpHcaiim ef ^ •

four planes,, but di£Fer.iD the application of the planes ctf acuminaticMi, which in the former arc'Set on the lateral planes, and in the latter on the, la- teral edsres.

. fcj The summit of the Acuminatian, which- sa either obtuse^ as in hexahedi;al prismatic Garnet;. rectangular, as in tetrahedral {Hrismatic Jai^on;- or acute, as in bexahedral prismatic Calcaijeous^ Spar.

Cd.J The magnitude of the aeuminatiim, by which is understood whether the acuQiination haa ^Qcroa^hed much or little on the primary form. ](lli rdatioxi to this a crystal is said to be slight^,. or deeply, acuminated. This distinctioiy however is confined to the p3'ramid and cube. . De^y acia^ SUQated is the cubical crystallization of Fluor-spar^ whose angles are acuminated by six planes; and slightly, Ihe trihedral pyramid of Grey^Copper-Ore, and of Copper-Pyrites,

(e.J The termination of the aaiminatian^ which is either a point or a line. The latter forms the transition to bevelling. The former is by far the most coifumoii, the latter occurs in hexabedral pris- matic White-Lead-Ore and Baroselenite, with both extreme planes obtusely acuminated by two large and two smaller planes, which termipate in a line.

§. 115.

In order to form a more distinct idea of trunca*

»

tion^ bevelling, and acumination, let us take a

*

cube»

cube, prisiUy pyramid or any other perfect primary form, represented in wood, and cut off each of the angles or edges at one stroke, so that in its stead a plane sliall appear; this will be truncation* But if the extreme planes, the edges, or the angles of any. of these primary forms be cut off with two converging strokes, the one from this side, the other from that, so that two planes arise, which, termi* nating in a line, shall present an edge; this wiU be bevelling. And if the extreme planes or the angles be cut xS -at several strokes, all converging toge* l^r, sQthat snofe dian two planes arise, commoor^ \y terniifiating in apoint, we shall obtain acuMio

DAtipO.

Manifold Modifications^

§. 116.

Many crystals of fossils occur with manifold and' repeated modifications. These are either situated

«

beside each other , by which we understand simple variations occurring in one and the same crystal and connected with each other, e. g. truncation of the edgei, acumination of the angles; or they are placed the one above the other ^ being simple varia* tions of the primary form modified by further va- riations, as e. g. the bevelling edges may be further bevelled, and these again truncated, &c. Crystals thus variously modified necessarily prove the most difi^cujt to describe.

§. 117*

19^ JSjfphctit^M ff tM

In describing a crystallization the number of its planes in general, and their figure if determinate^ may be mentioned by way of addition ; as e. g. cubical Galena, with truncated angles, consists of six octangular and four triangular planes.

To render the diescnption of a cryfllalHwdofi m dear as possible w« may ako, in toaw caies, adopt* Um diAirtait niodtt of d^larmiaing itH-tha rqfre^ seniative and deriaathe. By the representative » understood a description of a crystallization ac- cording to its apparent iTom, such as it seems at the first view ; by the d&rvoattve a description of a crystaHization founded on a joint consideration of its derivation and of its relation or affinity to the other crystals of the same fossil. Thus a de* scription of a prismatic crystallization of Tour* maline would be representatively an enneahedral prism, and derivatively a trihedral prism, with the three lateral edges bevelled ; thus also a pyramidal crystallization of Ruby would be representatively an unequt-lateral and equi-angular hexagonal table, with the extreme planes alternately set obliquely on the lateral planes; and derivatively ^ a simple trihedral pyramid with the angles of the base slightly truncated, and the summit so deeply truncated that

the

External Chardcfet$ 0/ FossHs. l«t

the kMrge fcruneating phne coojoias with \hm MMller.* The latter method^ vu« tlie derivative, is undoobt* edly the miMt applicaUe, being tiie most easj and iatefligible, and indeed the best adapted to tbe natoffe of tbe svbject. Generally speaking, however, ' oisr best guide in deternnning the prioiar j or fimda» mental form of a crystaUization is to consider-'— the Jlgwne and relations of tbe planes; the greater or less d^ee of regulariiy of the crystallization as ao« cording with that primary form from which it is sapposed to be derived ; tbe most '/raquant ag^ cmrence pi the crvstaUiaatioos ef the fossil ; tbe tfiniiy 6i the crysfeaUizafeion io the other erystab of tbe fossil ; ih^ smiabkness and peeuHarify of ita modifications ; and the greatest simpUiiitf ia the. mode of determination*

Transitums /roni one primary farm into another^

§. 193.

Through the forementioned modification of the primary form a gradual transition takes place from one primary form into another ; and this in pro- portion to tbe increased extent of the modifying planes, and tbe decreased extent of the primary planes. Indeed when the modifying planes ap- proach nearer to the center of tbe crystallization than tbe primary planes they become planes of the primary form; and conversely, the primary planes

'when

«

^ Tlipf crptal 11 comidered by Rome de Title at a section of tbe •ctabedron. Vid CryttaUog; TonL IL p. as;. Var. 6. Tk.

IM ExpUcaHm ^f tke

whrni more distant from the oenteir of the ' crystal* fixation than the modifying planes become planes of the truncation, acumination, and the like. A few examples will illustrate the subject : Galena has fi^e crystallizaticHis by which it passes from the perfect cube into the perfect double tetra- bedral pyramid, or octahedron. The perfect cube is its first .crystallization ; the second is the cube with slightly trnnoated angles ;. the. third is die cube with the angles so deeply truncated that the planes of truncation conjoin, forming the transition from the cube into the double tetrahe- dral pyramid, and which may be considered either as a deeply trnncaled octahedron, or as a deeply truncated cube ;. by extending the truncating planes we shall have the fourth crystallization, or. the double tetrahedral pyramid with truncated an- gles, in which therefore the truncating planes of the cube have actually become the primary planes of the octahedron, and conversely the primary planes of the cube have become the truncating planes of the octahedron, and thus a transition from the cube into the octahedron has already taken place ; by extending the truncating planes still farther, so that the primary planes disappear, we shall have the fifth crystallization, or the perfect double tetrahedral pyramid, in which the primary planes have totally disappeared, and the truncating planes only remain, now constituting the primary

^ planes

Extern^ Characters of Fossils. 195

planes of the octahedron.* The octahedron maf also be considered as the* first crystallization of Galena, fcdlowing its transition into the perfect cube through the intervening crystalKzatioos.

Farther, the oblique-angular tetrahedral prism of Arsenical-Pyrites with obtusely bevelled extreme planes (the bevelling planes being set on the acute lateral edges), passes gradually into the octahedron accordingly as' th^ prism beepknes shorter, and the bevelling |danes approach nearer to each other, so that at last their points conjoin. Here the. bevels Itng is the cause of transition, as in the preced- ing instance it was the truncation, f

Lastly, as examples of transition by acumination we may mention*— the tetrahedral prism of Tin- stone acuminated by four planes (the acuminating planes being set on the lateral planes), which passes into the octahedron, when the planes of acuniina« tion become more extended than the primary planes of the prism, the latter at length disappearing en- tirely

* In order to form a more diitinct concq;>tion of theie crytalU- sations and transittons of Galena, the reader may refer to tJbie ML and. and 3rd. Table of Linnzus, Systema Naturx, Tom. TIL in which the 19th. figure rcspresents the first cryttallization, the 40th. the teeond, the azit. the third, the a4th. the fourth, and the ft5th. the fifth. Ai far as my observation has reached, the difSsreDce in the crystallisations of Galena appears to me to be owing to the greater or less qoantity of silver which it contains, assuming the octohcdral form when most, and the cubical when least, argentiferous.

Vid. also the annexed PL 1. fig. 3, aj, 7,6, a^, and ij. ' tk.

tVid. PL a Fig. 51- Ta.

IM ExpUemiim ef 4#

tMyt^-die tctnhedral priflm of GwmtA acnwimtwri by four ptancs (the planet of acimiMtioQ beiog •et on cbo lateral edges), which paates into the ^odecahedion with rhomboidal planes, when th^ pffiMi becomes to .short that the acuminatiog planes conjoin t—«Bd thus, also, the bexahedial prism of Kock-crystal acuminated by six planes,* and the hezahedral prism of Calcareous^par acuminated by three planes^t pas8^--*tbe former into the AgM^ ble hexahedrai pyramid, aiud the latter into the double trihedral pyramid.

These examples may suffice to shew the transi- tion from one primary form into\another by means of truncation, bevdling, and acnmination*

f. 140.

But, a transition from one primary form into another takes place also from other causes, as —

4

from a change in the relative size of the planes; from a change in the angles under which the planes are associated ; from the convexity of the planes, and from the aggregation of crystals. Transitions by a change in the relative size of the pLuies occur in crys«^ tallizations of Apatite, which according to the greater extent of the lateral or of the extreme planes, may be termed hexahedrtil prisms or hexagonal ta*

bles ;

fT.PLtt Kg- 5«. T». |V. PLa Kg. 53* Ta.

♦Via.PL n. Kg. 54. Ta. \y. PL 0. F^ j^. Tk.

Extertud Cianciers qf FossUs. Iff

Was; aii4 tntDntioos by tbe aggregation of erys* tals occor in perfect hexagonal tables of Pranqmy which being aggregated by their lateral planes iMrm hexahedral prisms; and in perfect rectangu- lar qnadragonal tables of Yellow-Lead-Ore, wUc^ adhflriifg laterally to each other, form cubes*

§. 141.

In determining tbe fbrm of crystals yarious dliffi- cnlties frequently present themselves ; for sometimes they appear cmnpressedj some planes being nncom- flMXily ki^e or small; sometimes they are ftmnd fcneiratmg each ^iher, a principal hindrance in ascertaining the crystallization, and which firequently oocars in Tinstone crystals ; at other times they are foand partly concealed^ inhering in other fossils^ wUch is often die case with Felspar, Hornblende, and Garnet; and oftentimes they occur br&ken, a ¥ery common obstacle in ascertaining tbe crystal- lizatioB of precious stones ; and lastly they some** times occur t(w minute for description, in which case, boweiBer, the microscope may casually render aome serrice,

3. The aggregation of crystals.

^ 142.

We BOW come to consider- the aggregation of crystals, by which is understood whether a crystal is connected or unconnected with another fosnl or

crystal.

]gi £jtplicaHanqf iJk

crystal.. In this point of viesr all crystals oectfT either single or in aggregates. Single crystak are found,

1. Loose or detached ^ possessing their perfect crystallization, which were most probmbijr formerly inlaid in another fossil, but became, in covrae of time detached from it. In this state Precious Stones and Rock-crystal are particularly found, also Topaz, cxrtabedral Red*Copper*Ore from Siberia, cubical Mariial-Pyrites, and many others.

2. Inhering or inlaying in another fossil,- as crystals of Felspar in Porphyry ; of Hornblende in Basalt ; and hezahedral prismatic Quartz in Gyjn aam.

3» Adhering to another fossil, being attached by one end or side to another fossil, or to . the same uncrystallized fossil, and in such a manner that at the part of adherence the completion of the crys^ talis wssnting. Adhering are found simple py>^^ jDidal, and prismatic, crystals of Quartz, prisma** tic crystals of Arsenical-Pyrites, and many others.

-Aggregates, of crystals are regular^ or irregular.

Regular aggregates consist of a fixed numher of crystals aggregated in a determinate manner — ^such Are twin and triple crystals.

A twin^fystal is a peculiar aggregation of tiv^ crystals of the same fossil, and the principal dis- tinguishing marks of such aggregations are re-en- tering angles. As examples of twin-crystals — ^we faave ist. Stauroiite^ or the Cross-crystsJ of St. An*

dreansberg

External Characters of Fossils. Tj?

drea$berg in the Hartz» consisting of t^o very broad rectangular tetrabedral prisms^ each of which is acuminated by four planes which are set on the iMeral edges, and the two prisms intersecting each other longitudinally at right angles, form re-entering light angles ;-i.2nd . the twin-crystal of Gypsum> oomposfed of two hexahedral prisms, (each prism consisting of two broad and four narrow lateral planes, with' the extremities bevelled, and the bC'- veiling planes obliquely set, yet parallel to each other, on the broad lateral planes), and aggregated in such a manner by two narrow lateral planes^ that the bevelling plane% form at one extremity a salient, and at the other a re-entering, angle ;— - 3rd. the twin-crystals of Ruby, composed of two simple trihedral pyramids attached by their bases, with the angles of the base slightly truncated (and hence forming . at the base obtuse re-enteridg angles)) and the summits of both pyramids so deeply truncated as to present rather a tabvlar appearance. The two pyramids are sometimes also so disposed by their bases upon each other that the angles of the one project over the sides of the other. Sometimes the summit of only one of the pyramids is deeply truncated, in which case the twin-crystal has the appearance of a simple trihedral pyramid with the angles and sumoHt slightly truncated, possessing at the base an equi-angular but uoequi-laterai hexagonal table, whose extreme

K alternately

130 Explication qf the

pknes are alternately obliquely set on the lateral planes.*

A iripU'Crystal is a peculiar aggregation of three crystals of the same fossil. These are very rare and have hitherto occurred in Calcareous-Spar and Ruby only. The triple-crystal of Calcareous- Spar is composed of an equi-lateral hexagonal table, with an equi-angular but unequi*lateral hexagonal table adhering to either lateral plane ;f the tri- ple-crystal of Ruby is in other respects the same as the last mentioned modification of the twin- crystal, only that to one of the lateral planes of the slightly truncated pyramid there adheres an elongated' hexagonal table, with alternate obliquely applied extreme planes.

«

Irregular aggregates are composed of an inde- terminate number of crystals, singhf or daubh/ ag- gregated.

Aggregates consisting of many singly aggregated crystals may be distinguished into such as are,

I. Heaped one upon another, which occur only in crytals of equal dimensions, and particularly in

those

* Rome dt VUlc has shewn that the twin-ciTstal of Ruby arises from the section of an octahedron in an obliqbe direction, parallel to two opposite planes of the two pyramids; the situ- ation of the two halves of the octahedron being changed in rela- tion to each other. Vid. Crystallog. Tom. II. p. 227. Var. 7. Vid. also Hauy Traite de Mincralogie, Tom. 11. p. 449, Spinelle trans- pose. Tr.

f Proceeding probably from a regular hexagonal table includ- ing a very low hcxaliedral prism, witli alternate broad and nar- row lateral planes; the terminations of the prism appearing on the lateral planes of the table. Ta.