174 A SYSTEM OF 



ture. The more copper it contains, the 

 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 y 

 or Ruffigtes-Ertz. 



b. Solid, of a light-grey colour, and is 

 that fort properly lb called WeifTgulden. 



It is found at St. Mary of the mines 

 in Alfatia, the Saxon mines, and at St. 

 Andreafberg in the Hartz. 



SECT. CLXXIL 



4, With fulphurated arfenic and iron, Ar- 

 gentum ferro iff arfenic fulphurato miner alt- 

 fatum^ The Weifertz^ or white filver ore, 

 of the Germans. 



This is an arfenical pyrites, which con- 

 tains filver ; it occurs in the Saxon mines, 

 and fo exacfly refembles the common ar- 

 fenical pyrites as not to be diftinguiihed 

 from it by fight alone, or without other 

 means. The filver it contains may per- 

 haps confift of very lubtile capillary filver 

 mixed in it. However, I have not had an 

 opportunity to examine this circumftance. 



SECT CLXXIII. 



5. With fulphurated antimony, Argent um 

 anfimonio fulphurato miyieralifatum, 



a. Of a dark-grey and fomewhat brownifh 

 colour. The Lebererz, from Braunl- 

 d'orff in Saxony. 



b. Of a biackifh blue colour, 



I. In 



