'.57 
MINERALOGY. 
SECT, L. 
Quartz, ^artzum^. 
This ftone is very common In Europe^ 
and eafier to be known than defcribed. It 
is diftinguiihed from the other kinds of 
the filiceous order, by the following qua- 
lities. 
1. That it is moft generally cracked 
throughout, even in the rock itfelf, 
whereby 
2. As well as by its own nature, it breaks 
irregularly, and into lharp fragments. 
That it cannot eafily be made red hot, 
without cracking ftill more. 
4. It never decays in the air 
5. Melted with pot-aihes, it gives a more 
folid and fixed giafs than any other of the 
filiceous order. 
,6. When there has been no interruption in 
its natural accretion,' its fubftance always 
criilaliifes into hexagonal prifms, pointed 
at one or both ends. 
7. It occurs in clefts, fifTiires, and fmall 
veins in rocks. It very feldom forms 
large veins, and ftill feldomer whole 
mountains, v/ithout being mixed with he- 
terogeneous fubftances. 
SECT. XL 
The Quartz is found, 
j. Pure, ^lartzum punim. ■ ' 
A, Solid, of no vifible particles with a 
gloflyTurface.- Particulis impalpabilihus 
fuperficie polita. f'at Quartz. 
* I fhall adopt this name of quartz inEnglifh as it has al- 
ready gained a;cefs into the other European languages. D. C, 
a, unr. 
