SILVER. 121 



Bromyrite or Bromic Silver. Silver united with bromine. Ag Br= 

 Bramine 4^ "6, silver 57*4=100. Occurs with the preceding in Mexico 

 and Chili. 



Embolite. A chlorobromide of silver, resembling the chloride or horn 

 silver. Color asparagus to olive green. Contains 51 of chloride of sil- 

 ver, to 49 of bromide. This ore is not less common in Chili than the 

 chloride. It has also been found in Chihuahua, Mexico. 



Iodyrite. A silver iodide, Ag 1= Iodine 54*0, silver 46 '0 = 100. It 

 has a bright yellow color. From Spain, Chili, Mexico, and the Cerro 

 Colorado Mine in Arizona. 



Tocornalite. A silver-and-mercurv iodide from Chili. 



General Remarks. — The chief sources of the silver of commerce are 

 (1) Native silver ; (2) the sulphide, Argentite (or vitreous silver), com- 

 mon in Mexico, and also in the Humboldt, Reese River mining dis- 

 tricts ; four species among the sulpharsenites and sulphantimonites, 

 viz., (3) Proustite or the light red or ruby silver ore, and (4) Pyrar- 

 gyrite, or dark red silver ore, both common in Chilian, Peruvian, 

 and Mexican mines ; (5) Freieslebenite ; (6) Argentiferous tetreihedrite, 

 which contains sometimes 10 to 30 per cent, of silver, abundant at 

 some Humboldt County, Nevada, mines, at Colorado silver mines, and 

 at various Chilian, Bolivian and Mexican mines, as well as in some 

 silver mines of Europe ; (7) Stephanite or brittle silver ore, common in 

 Nevada, Colorado, and at the Washoe mines, Western Utah ; (8) the 

 chloride, called horn-silver or Cerargyrite, common in Chili, Mexico, 

 Idaho ; (9) the bromide and chlorobromide, Bromyrite and Embo- 

 lite, common in Chili and Mexico, especially the latter, along with 

 the rarer iodide; (10) Argentiferous Galenite, the lead ore, galenite, 

 even when containing but 5 ounces of silver to the ton, being profita- 

 bly worked for its silver. The other ores of silver mentioned beyond 

 are seldom of great abundance. The most important of them are sil- 

 ver amalgam or A rquerite, common especially in Chili, and Polybasite. 



Silver ores occur in rocks of various ages, in gneiss and allied rocks, 

 in porphyry, trap, sandstone, limestone, and shales ; and the sand- 

 stone and shales may be as recent as the Tertiary. The veins often 

 intersect trachytic, porphyry, and other eruptive rocks, or the sedi- 

 mentary formations in theVicinity of such rocks, and have owed their 

 existence in many cases to the heat, fracturing, and vapors from 

 below, attending the eruptions. 



Silver ores are associated often with ores of lead, zinc, copper, co- 

 balt, and antimony, and the usual gangue is calcite or quartz, with 

 frequently fluor spar, pearl spar, or heavy spar. 



Ihe silver of South America is derived principally from the horn 

 silvers, stephanite, ruby silver, vitreous silver ore, and native silver. 

 Those of Mexico are of nearly the same character. Besides, there are 

 earthy ores called color ados, and in Peru pacos, which are mostly 

 earthy oxide of iron, with a little disseminated silver ; they are found, 

 near the surface where the rock has undergone partial decomposition. 

 The sulphides of lead, iron, and copper of the mining regions, gene- 

 rally contain silver, and are also worked. 



In South America the Chilian mines are on the western slope of the 

 Cordilleras, and are connected mostly with stratified deposits, of a 

 shaly, sandstone, or conglomerate character, and their intersections 



