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270
MINERAL RESOURCES, 1912.
the copper or lead bullion that collects the precious metals in the smelting. The total quantity shipped of this class of ore decreased from 6,016,425 short tons in 1910 to 5,588,771 tons in 1911, but increased to 6,543,436 tons in 1912. The increases for 1912 were mainly in Alaska, Arizona, Colorado, Idaho, Montana, Nevada, and New Mexico; and the decreases were chiefly in California and Utah. The tonnages are notably large in Arizona and Utah and the bulk of the precious metal bearing ores of the Eastern States are smelted crude. The total gold output from crude ores smelted decreased from 623,272 fine ounces in 1910 to 611,344 ounces in 1911 and to 578,391 ounces, valued at $11,956,403, in 1912, the decreases being chiefly in California, Idaho, Montana, Nevada, Utah, and Washing­ton, and the increases in Alaska, Arizona, Colorado, New Mexico, Utah, and Washington. The total recoverable silver output in crude ores shipped to smelters increased from 28,487,837 fine ounces in 1910 to 29,831,111 ounces in 1911 and decreased to 29,729,092 ounces in 1912. The increases in 1912 were chiefly in Alaska, Arizona, Colorado, New Mexico, Utah, and Washington, and the decreases in California, Idaho, Montana, Nevada, Oregon, and South Dakota.
Under the fifth item is given the quantity of old materials, princi­pally slags and tailings, re-treated, and their recoverable contents. These are largely smelted, sometimes mainly for their fluxing values, but increasing quantities of old tailings are now concentrated and cyanided, as in the case of Cripple Creek. The Colorado tailings treated are included in the first column of the table with crude ore. The concentrates produced from old tailings, and their gold and silver content, are included under "Concentrates produced." Comparison of the figures for 1911 and 1912 shows that the total quantity of this old material treated (excluding that in Colorado) increased from 412,346 short tons in 1911 to 476,730 tons in 1912, but that the recovered gold content decreased from 16,259 to 15,614 fine ounces and that the silver recovery increased from 99,475 to 775,198 fine ounces.
From this table the output of ore from the Central States, produc­ing insignificant quantities of silver and no gold, has been omitted. The output of zinc ore from the Eastern States is also omitted, as this zinc ore is reported to produce no silver or gold.
The following table shows in summary the percentage of total output, by processes, of gold and silver in the United States in 1911 and 1912: