“MINERALOGY. 
436 
many diverfifications as there are fpecies of animals and 
•vegetables. The intelligent inveftigator will not there¬ 
fore ftraiten the limits of an ufeful fcience, by difregard- 
ing the ancient inhabitants of the globe, though unknown 
to modern naturalifts. The modes of petrifa&ion are 
principally fourfold; Foffils, fubftances reftored, fub- 
ilances imprefl'ed, and fubftances tranfubftantiated ; and 
are more frequent in Marble, Fiint, Schift, Sand-ftone, 
Rock, and Quartz. 
The difficulties of fcience have moreover produced 
various paradoxes. Confolidated fiffures of rock are often 
diftir.Clly viftble; but by what means or power they have 
been broken, is not eafily demonftrated. All Spar is ge¬ 
nerated by cryftallization in cavities filled up; nor is Spa- 
tum ever prelent without rhombs ; but how it is broken 
into rhombs, or how from a cubico-muriatic is produced 
a rhombic figure, is.not very evident. Amiantus is ob- 
ferved to be regenerated from the earth of Talc, the caule 
of which is oblcure. That Molybdsenum is metallic can¬ 
not be doubted, and it has often been aflerted to be im¬ 
pregnated with Zink or Tin ; yet it is not eafy of proof, 
jews-ftones are found petrified in hollow cavities, gene¬ 
rated from a fluid with fpar, of which they often entirely 
to nil ft: but from what animal they have their origin is 
not fufficientiy evident, iince the Echini do not afford a 
fktisfaClory elucidation. 
Primary Salts have a peculiar and determinate figure; 
but, when changed, often appear with a different, but 
alike determinate, figure ; but from what mixture proper 
to themfelves, or from what extraneous terrene mixture, 
the ftudent in this department has not been able to de¬ 
termine ; and, fince metals are generated from falts by 
cryftallization, alchemifts have in vain laboured at the 
true transformation of metals; and this metamorphofis 
of falts muft remain tindifcovered, fo long as metallur- 
gifts lliall negleCl it, and turn their inveftigations towards 
garths only. 
Similar ftrata of the earth are often obfervable in broken 
(mountains ; but it is not evident that they are all of the 
fame genus, or produced from the waters of the ocean, 
The lowermoft ftratum o (Sand-ftone. The fecond of Schijl. 
The third of Marble, with marine petrifactions imbedded, 
and often extraneous matter. The fourth of Schiji. The 
fifth and uppermoft of Bock, often of vail bulk. 
It is palpable to common obfervation, that the Ocean 
5 s the mother of the Earth. The waters of ocean, made 
Surbid by nitrous Ihowers, are precipitated and cryftal- 
Jized into fand which covers the bottom of the fea. The 
ocean is here and there, in vaft patches, overfpread with 
the Fucus natans, caufing tranquillity on its furface, 
unlefs when agitated by variable winds. The foil from 
decayed Fuci gradually defeends, being lighter than fand, 
while this marine vegetable gradually dilates itfelf into a 
floating meadow. Marine worms, mollufcae, teftaceous ani¬ 
mals, lithophytes and zoophytes, fifties with their floating 
eggs, and fea-birds whole formation renders them unfit for 
flight, feed under this marine meadow of Fucus. Under 
the waters in a Hate of tranquillity is Ihowered down an 
argillaceous fediment with the calcareous fliells of gradu¬ 
ally-corrupting worms, till an elevated accumulation is 
formed parallel with the furface of the fea, while its pref- 
iure, moving the waters, repels the marine fubftances 
around it. For the formation of Rock, according to its 
own laws, the fea firll calls up vail mafl’es of Fuci, which 
moulder into loil, clothing the naked earth at the bottom 
with an arenaceous covering, at firll eafily blown about 
when dry, and when mixed concreting into gravel, and 
ultimately into rocks. 
By a long fucceffion of ages therefore, and by a peren¬ 
nial quiefcence of feafons, Sand is concreted into Saud- 
Jlone, varioully but properly cleft. Soil is cemented into 
Schiji, lamellous and combuftible. Clay is indurated into 
Marble, coagulated by worms. Soil is cemented into an 
upper ftratum of Schiji, lamellous and combuftible like 
&he former. Sand is concreted into Gravel, with a mix¬ 
ture of other fubftanees. This again Is concreted into 
fmaller Hones, thefe into larger, and thefe iaft into rocks; 
till at length, the waters of the fea gradually fubfiding, 
there appears a mountain : nor can the higheft rocks float 
upon an argillaceous furface, while, before it became cal¬ 
cified, marine worms continue their growth in it. That 
the higheft roc)cs therefore are the genuine offspring of 
time, while all was filence, themfelves fufficientiy declare. 
Such are the mutations produced by the laple of time. 
It is very rarely, and indeed fcarcely ever, that the 
Species can be fufficientiy determined, fince in thefe the 
generation proceeds not from the egg ; but the multi¬ 
plied variety of irregularly-fportive nature, is at once the 
calamity of the fcience and the foundation of metallurgy. 
He therefore, that fhall rafhly endeavour to multiply the 
fpecies, is not lefs abfurd than him who combines fub¬ 
ftances totally different in nature. Nor does their matrix 
diftinguifh the different fpecies, more than their natural 
fituation and foil do the plants of the earth. The numer¬ 
ous diverfities of Hones, therefore are principally varie¬ 
ties ; in the arrangement of which, without caution, it is 
eafy to fall into error. 
The ftudent has three modes of inveftigating this King¬ 
dom : Phyjical, which defeends through the obfeure ge¬ 
neration of minerals ; Natural, which confiders their fu- 
perficial and vilible ftru&ure; Chemical, which afeends 
through their deftruefive analyfis. In this then, as in 
every thing elfe, he will molt fafely purfue the middle 
courfe; and, by clofely following his aria'dnean thread, 
he will not, like an empyric, confound the lymptoins 
with the cure, nor bring forward the doubtful progeny 
of a long-loft anceftry; much lefs will his terrified ima¬ 
gination raife up fanciful fpefitres in the dark, or perfuade 
him that the Phoenix of the poets may be regenerated 
from its own afhes ; but he will learn, what names are re¬ 
pugnant to things, and what are convenient; and how to 
define characters by their diagnollics, and not merely by 
their etymology. Syfk Nat. tom. iii. 
Thus in looking at even a fmall collection of minerals, 
with a view to the defeription of them, it is obvious thaf 
the varieties in any one of their external charaClers are 
very numerous. Various lhades of colour for inftance, 
and various modifications of form, are continually pre- 
fenting themfelves ; and confequently the variety in the 
deferiptive language, where accuracy is aimed at, muft be 
proportionately great; and it is on this account that, in 
mineralogical treatifes, we meet with thofe numerous 
combinations of deferiptive epithets which are fuggefted 
by the endlefs variety of colour, texture, confidence, and 
in ffiort of every feparate character of a mineral. On many 
occafions thefe dilcriminations have been carried to a te¬ 
dious and nearly ufelefs length ; and principally in the 
defeription of colour, which, of all the characters of a mi¬ 
neral, is perhaps the leall important; a difference in this 
relpeCt often depending on caufes too trifling to interfere 
with the real nature of the lubftance in which it occurs. 
Thus in the fapphire and the ruby the colour is widely 
different, though the chemical analyfis is nearly the fame. 
The characters which it is moil important to afeertain 
in the examination of minerals are, their degrees of fufi- 
bility, their hardnefs, phofphorelcence, eledftricity, their 
refraClive power with refpeCt to the rays of light, their 
fpecific gravity, and their cryftalline form; to which 
Ihould be added, as often as poffible, the refults of their 
chemical analyfis. 
The moll ready way of afeertaining the fufibility of a 
mineral fubftance is, by expofing a fmall particle of it to 
the flame of a candle or lamp concentrated by the inftru- 
nient called a blowpipe ; and, if the heat thus excited i® 
fufficient to liquefy the mineral, it is laid to be fufed. It 
muft be obferved, however, that the effeCl of fufion does 
not entirely depend, in all inltances, on Ample heat; for 
many earthly fubftances refill a very conliderable degree 
of heat if placed in contaCl with charcoal, or a metallic 
lubftance, which, if expoftd to the Fame heat in contact 
