( XY ) 
idoms, as are not ufnally foiind in their natural 
ftate, and in this refped; they belong properly 
to the ftudies of the Botanift^ and Zoologifts, 
For a Mineralift is fatisfied with ^ fingle fpeci- 
rnen of each different fubftance tk^t has taken 
the fhape of a vegetable or animal body, and 
this only to illuftrate the hiftory of ^eir ge- 
neration ; he leaves it to others to decide if 
corals are vegetables, or the habitations of 
worms ; and thus receives them very uncon^ 
^:emedly, after they have been mouldered to a 
chalk, changed into a fpar, or into any other 
ftony matter. Neverthelefs, I have in the 
Appendix propofed a method for ranging the 
Saxa and PetrefaBa in regard to the oeconomical 
pfes that may be expedted from them, 
Slate fignifies or denotes the form alone, and 
not its kind or qualities ; however, it regards 
only its fituation in the rock, and not the tex- 
ture of its particles j which latter I have always 
endeavoured to take notice of, fince fome dif- 
ference in the effedts frequently depends on it. 
And, as nothing is great or fmall but by com- 
parifon, it is difficult ftridtly to determine ip 
what degreg of thicknefs or thinnefs a ftone 
begins to deferve the name of a flate. Never- 
thelefs, I would have prevailed on myfelf to 
^dopt this general name, if the breaking iqi 
Ihin plates had been the property only of 
pny particular kind of ftone, but it is by no 
means the cafe ^ becaufe there is found in the 
province of Jemteland, in Sweden, a pure 
quartz, limeftone, (bpth fplid and fcaly) indu- 
