SILVER. 121 
Bromyrite or Bromic Silucr. Silver united with bromine. Ag Pr= 
Eromine 42°6, silver 57-4=100. Occurs with the preceding in Mexico 
and Chili. 
Hmbolite. 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 isnot less common in Chili than the 
chloride. It has also been found in Chihuahua, Mexico. 
dodyrite. A silver iodide, Ag I=Iodine 54:0, silver 45°0=100. It 
has a bright yellow color. From Spain, Chili, Mexico, and the Cerro 
Colorado Mine in Arizona. 
Tocornalite. A silver-and-mereury 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, keese River mining dis- 
tricts ; four species among the sulpharsenites and sulphantimonites, 
viz., (8) 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) Freteslebenite ; (6) Arg ntiferous tetrahedrite, 
which contains sometimes 10 to 80 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 Cerargyritc, common in Chili, Mexico, 
Idaho; (9) the bromide and chlorobromide, Bromyrite and Hindo- 
dite, 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 arc sil- 
ver amalgam or Arquerite, common especially in Chili, and Polybasiic. 
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 asthe Tertiary. ‘The veins often 
intersect trachytic, porphyry, and other eruptive rocks, or the sedi- 
mentary formations in the vicinity 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 hcavy spar. 
The silver cf South America is derived principally from the horn 
silvers, stephanite, ruby silver, vitreous silver ore, and native silvcr. 
'!hose of Mexico are of nearly the same character. Besides, there are 
earthy ores called colorudos, 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. 
‘he 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 
