f xvl ] 
rated boles, alum o/es, and a great number of 
faxa, which are airof a plated ftrudure, dividing 
into leaves as thin as pafteboard : And there- 
fore I make no doubt but ail kinds of ftones 
may be found of fuch a figure in fome parts of 
the world; What confufion would it not occa- 
iion if all thefe different kinds were included 
tinder one genus? And are there not folid 
ftones found confiding of the fame conftituent 
parts as the flates, which are feparately confi- 
dered in fyftems ? 
I could not range the ores according to the 
different kinds of rock in which they are found 5 
for inftance, the Goofe-dung filver ore, the Liver 
ore, and many more of the fame kind, fince' 
obfervations upon the matrices of ores belongs 
to another branch of the Mineral Science, called 
Geographia fubterraneay or Cofmographia fpe- 
cialis^ in which likewife the clefts, filTures, 
and veins or loads, that occur in every fort of 
rock, (in order to promote the circulation and 
fixation of the mineral vapours) are treated of. 
In that Science alfo the Petr(^ Parafiticce arc 
pointed out, whofe number perhaps is not yet 
known ; as likewife the glofly fififures fron^i 
which the Minerce Speculares have obtained 
their name. And this is a branch of fcience^ 
which, in the hands of a Ikilful mineralift, is 
likely to furnifh us with a perfedl idea of the 
age of every fort of ftone, and alfo of their 
different gradations between the two accidents, 
to which all created beings are fubje^l, Com^ 
pofition and Deftruilionp 
Since 
