Portal logo
GOLD AND SILVER.
611
district, Mont. In 1917 the copper ores of the United States pro­duced more than 8.7 per cent of the total gold,, against 9 per cent in 1916. The natural tendency is for the proportionate output from gold ores to decrease, with declining yield from some of the principal gold camps, and for that from copper ores to increase, with a general net falling off of total yield of gold owing to the preponderant output from gold and gold-silver ores.
The principal domestic supply of new silver comes from dry or siliceous silver and silver-gold ores, from copper ores, from lead ores, and from lead-zinc ores—in the proportion of 30.4, 28.8, 27, and 12.2 per cent, respectively, in 1917, against 31.2, 31.1, 24.4, and 10.9 per cent, respectively, in 1916. The dry or siliceous silver-gold ores have come chiefly from four large mines of the Tonopah district, Nev., and declining output from this camp more than offsets gains from such ores elsewhere. The bulk of the silver ores of this class are milled and cyanided at or near the mines, although a small quantity of richer ores is shipped to copper and lead smelters. The largest single producer of silver in 1917 from domestic mines was the Anaconda Copper Co., of Montana, producing from copper ores; the second largest was the Hercules Mining Co., of Idaho, producing from lead ores; and the third largest was the Tonopah Belmont Mining Co., of Nevada, producing from siliceous ores. Of the 25 mines or groups of mines producing silver on the largest scale, 8 were silver-gold and silver mines, 6 were copper mines, 10 were lead mines, and 1 was a zinc-lead mine. With large recent increase in output of argenti­ferous copper, lead, and zmc-lead ores, the domestic silver output has been fairly well maintained against decline from silver-gold and (the rare) silver ores. The silver obtained as a by-product from copper, lead, and zinc ores is derived from refining the copper and lead bullion produced in smelting those and other ores.
WORLD'S PRODUCTION OF GOLD.
The peak of the world's production of gold was reached in 1915 (see PL IV), when most of the great gold fields were contributing maximum outputs. In 1916 declines in the United States, Russia (and Siberia), and Australasia more than offset an increase in Africa.