A SYSTEM OF 
96 
Is diftinguiflied from the martial glim- 
mer, or mica, (Sedl. xcv.) by the fcales 
being lefs fliining, thicker, and rectan- 
gular. 
a. Black. This, when riibbed fine, gives a 
green powder. 
Greenifti. 
Both thefe, particularly the black, are 
found every where in Sweden among the 
iron ores, and in the Grunften (Sedlion 
cclxix 
c' 
SECT. LXXXIX. 
JD. Tripoli, Terra Tripolit ana. 
- Is known by its quality of rubbing hard 
.. bodies, and making their furfaces to fiiine, 
the particles of the tripoli being fo fine, as 
to leave even no fcratches on the furface. 
This efiedl, which is called polifiiing, may 
iikewife be effefted by other fine clays, when 
they have been burnt a little. The tripoli 
grows fomewhat harder in the fire, and is very 
refradlory : it is with difficulty difiblved by 
borax, and ftill with greater difficulty by the 
microcofmic fait : it becomes white v/hen it is 
heated : when crude, it imbibes water, but 
is not diffufible in it : it taftes like common 
chalk, and is rough or fandy between the 
teeth, although no fand can by any means be 
feparated from it. It has no quality common 
^ The hornblende grows hard in the fire, which is the rea- 
fon why it is ranked here among the clays, though in all its. 
other qualities it much refembles the cockle or fliirl. (Sedion 
Ixxii.) E, 
with 
