174 - 
A SYSTEM OF 
ture. The mare copper it contains, th^ 
darker is the colour. It often holds feven 
' pounds of filver per cent. It is, 
a. Friable, withered, or decayed^ of a 
black or footy colour, and is therefore 
by the Germans .called Silber-Schwartz^ 
or Rujfigtes-Ertz, 
h. Solid, of a light-grey colour, and is 
th^t fort properly fo called WeifTgulden. 
It is found at St. Mary of the mines 
in Alfatia, the Saxon mines, and at St. 
Andreaiberg in the Hartz. 
SECT. CLXXIL 
4. With fulphurated arfenic and iron, Ar- 
gcntum f err 0 fs? arfenico fulphurato miner ah- 
fatum^ The fVeifertz^ or white fiiver ore, 
of the Germans. 
This is an arfenical pyrites, which con- 
tains filver ; it occurs in the Saxon mines, 
and fo exa( 5 tly refeitibles the common ar- 
fenical pyrites as not to be diflinguifhed 
from it by fight alone, or without other 
means. The filver it contains ma}?" per- 
haps confift of very fubtiie capillary filver 
mixed in it. However, I have not had an 
opportunity to examine this circumftance, 
SECT. CLXXIII. 
5. With fulphurated antimony, Argentum 
antimoniQ fulphurato mmeralifatum. 
a. Of a dark-grey and fomewhat brownifh 
colour. The Leber erz^ from Brauni- 
dorff in Saxony. 
h. Of a blackifii blue colour. 
X. In 
