Silver Ore

any of the natural mineral formations containing Ag in such compounds and quantities that commercial use is technically feasible and economically profitable. The principal minerals of silver ores are argentite, pyrargyrite, polybasite, proustite, stephanite, and silver-bearing galena. The ores often contain native silver. Silver ore deposits are most closely associated with granitoids, as well as with subvolcanic and volcanic rocks, occurring either in these rocks or in the surrounding rocks. In the belt of silver-bearing deposits stretching for 4,000 km across North and South America, silver ores are present in lead, lead-zinc, gold-silver, and silver deposits (Pachuca, Guanajuato, and Zacatecas in Mexico; Cerro de Potosí and Cerro de Pasco in Peru; Potosí in Bolivia).

Silver deposits as such are relatively rare and count for little in total world supply and output. Between 80 and 90 percent of the silver is extracted as a by-product from deposits of complex ores, mainly from lead-zinc (45 percent), copper (18 percent), and gold-silver (10 percent) ores. Between 10 and 20 percent is extracted from silver’s own ores. The lower limit of Ag content in deposits deemed economically profitable to extract varies from 45-50 to 350 grams per ton.

Annual silver production in capitalist and developing countries amounts to 7,000-8,000 tons; proven and potential reserves of silver in these countries are put at 110,000 tons, including reserves of 40,000 tons in the United States, 23,000 in Mexico, 20,000 in Canada, and 16,000 in Peru). Canada, Peru, Mexico, the United States, and Australia lead the world in the mining and production of silver. In the USSR, silver is chiefly extracted from complex and gold-silver ores.