ORDER IX. PRISMATIC ANTIMONY. 429 



OBSERVATIONS. 



1. The Arsenical Silver is considered by Professor HAUS- 

 MANN as a more or less intimate mechanical mixture of 

 native Arsenic or of prismatic Arsenical- pyrites with pris- 

 matic Antimony ; and several mineralogists have regarded 

 the Antimonial Silver and the Arsenical Silver as varieties 

 of the same species. Very few of their properties have 

 yet been ascertained ; among those which are known, the 

 curved lamellar composition peculiar to Arsenical Silver, 

 and its readiness to assume grey tarnished colours, the 

 last of which, however, is, perhaps not without foundation, 

 ascribed to native Arsenic, perhaps also specific gravity, 

 may serve to distinguish it from Antimonial Silver. It 

 appears, therefore, that an accurate examination of both 

 substances is a thing yet very much wanted. 



Antimonial Silver occurs in crystals and massive varie- 

 ties consisting of granular individuals ; Arsenical Silver is 

 found in curved lamellar compositions, consisting of very 

 thin crystalline coats. These are subject to tarnish. 



2. According to KLAPROTH, the Antimonial Silver con- 

 sists of 16-00 to 24-00 of antimony, and 84-00 to 76-00 of 

 silver; the Arsenical Silver, according to the same au- 

 thor, of 



Arsenic 35-00. 



Antimony 4-00. 



Silver 12-75. 



Iron 44-25. 



Before the blowpipe the pure varieties yield a globule of 

 silver, while the antimony is driven off. 



3. It is found in veins, accompanied by hexahedral Sil- 

 ver, native Arsenic, hexahedral Lead-glance, and various 

 other species. Antimonial Silver is found at Altwolfach in 

 Fiirstenberg, and Andreasberg in the Hartz ; Arsenical Sil- 

 ver, also in the Hartz, and Guadalcanal in Estremadura in 

 Spain. 



4. It is a rare mineral, and is highly valuable for extract- 

 ing silver, wherever it is found in sufficient quantity. 



