GUIDE TO THE MIXER ALOGIC COLLECTIONS 61 



in Canada, in parts of New England and in Orange and Putnam 

 counties, N. Y. 



Arsenopyrite is an ore of arsenic. 



Sylvanite (graphic tellurium) (AuAg) Te 2 



Sylvanite represents a group of gold and silver tellurids 

 which has recently developed to considerable importance in the 

 Cripple Creek district of Colorado. Sylvanite contains G2.1$ 

 tellurium, 24.5$ gold and 13.4$ silver. 



It occurs in flat monoclinic crystals usually grouped in branch- 

 ing forms resembling written characters, it is silver-w T hite to 

 steel-gray in color, inclining to yellow, and has a brilliant 

 metallic luster. 



Sylvanite occurs in Transylvania, California and Boulder 

 county, Col. where it is mined for gold. 



SULFO-SALTS 

 SULFARSEXITES, SULFAXTIMONITES, ETC. 



Bournonite (wheel ore) PbCuSbS 3 



Bournonite is a sulfantimonite of lead and copper and con- 

 tains 42.5$ lead, 13$ copper, 24.7$ antimony and 19.8$ sulfur. 



The orthorhombic crystals are frequently twinned, producing 

 the "cogwheel" forms from which the species derives its com- 

 mon name. It frequently occurs massive, granular or compact. 

 The color is steel-gray to dark gray and the luster metallic. 



Bournonite is found in Germany, Bohemia, Hungary, Corn- 

 wall, Mexico, Chile; also in Canada, Arizona, Arkansas and 



Colorado. 



Pyrargyrite (dark ruby silver ore) Ag 3 SbS.> 



Pyrargyrite is a sulfantimonite of silver and contains 17.8$ 

 sulfur, 22.3$ antimony and 50.9$ silver. 



Pyrargyrite crystallizes in the rhombohedral-hemimorphic 

 group of the hexagonal system. The crystals are prismatic 

 with rather flat terminations and are frequently twinned. It 

 is translucent to opaque, of a deep red color by transmitted 

 light and gives a purplish red streak. The luster is metallic 

 to adamant inc. 



