120 DESCRIPTIONS OF MINERALS. 



Obs. It occurs with other silver ores at Freiberg, Schnee- 

 berg, and Johanngeorgenstadt, in Saxony ; also in Bohe- 

 mia" and Hungary. It is an abundant ore in Chili, Peru, 

 and Mexico, and also in Nevada, and at the Comstock Lode, 

 and at Ophir, and Mexican mines, in the Reese River and 

 Humboldt, and other regions ; in Colorado and Idaho. It is 

 sometimes called black silver. 



Polyhnsite is near stephanite in color, specific gravity and composi- 

 tion, but contains some arsenic and copper, with. 64 to 72 "2 per cent, of 

 silver. The crystals are trimetric, and usually in tabular hexagonal 

 prisms, without distinct cleavage. G. =6,214. From Freiberg, Przi- 

 bram ; Mexico and Chili; the Reese mines in Nevada, and Idaho. 



Miargyrite is an antimonial silver sulphide, containing but 36"5 per 

 cent, of silver, and having a. dark cherry-red streak, though iron-black 

 in color. B.B. on charcoal gives off fumes of antimony and an odor 

 of sulphur ; and in the oxidating flame, a globule is left which finally 

 yields a button of pure silver. 



Brongniardite occurs in regular octahedrons and massive, grayish- 

 black in color, and contains about 25 per cent, of silver, with lead, an- 

 timony, and sulphur G.=5*95. From Mexico. 



Poly argy rite also is isometric, having cubic cleavage, and is from 

 "Wolfach in Baden. It is near polvbasite in composition = 12 Ag 2 S-h 

 Sb 2 S,. 



Frtieslebcnite is a monoclinic antimonial silver-and-lead sulphide, of 

 a light steel-gray color, with G. =6-6*4. Contains 22 to 24 per cent, 

 of silver. From Saxony, Transylvania, and Spain. 



Pyrostilpnite is another monoclinic silver ore ; its delicate crystals 

 are grouped like stilbite and have a fire-red color. Contains 62*3 per 

 cent, of silver. From Freiberg, Andreasberg, and Przibram. 



Cerargyrite. — Horn Silver. Silver Chloride. 



Isometric. In cubes, with no distinct cleavage. Also 

 massive, and rarely columnar ; often incrusting. Color 

 gray, passing into green and blue ; looks somewhat like horn 

 or wax, and cuts like it. Lustre resinous, passing into ada- 

 mantine. Streak shining. Translucent to nearly opaque. 



Composition. Ag CI = Chlorine 24*7, silver 75*3. Fuses 

 in the flame of a candle, and emits acrid fumes. B.B. af- 

 fords silver easily on charcoal. The surface of a plate of 

 iron rubbed with it is silvered. 



Obs. A very common ore and extensively worked in the 

 mines of South America and Mexico, where it occurs with 

 native silver ; and also abundant in Xevada about Austin, 

 Lander Co. ; in Idaho at Poor Man's Lode ; occurs also in 

 Comstock Lode ; and in Arizona ; also at the mines of Sax- 

 ony, Siberia, Norway, the Hartz, and Cornwall. 



