Ch. 1: Gold and Silver in 1911

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	252	MINERAL RESOURCES.

	recorded for most of the other States, notably Utah. The total silver production from crude smeltmg ore increased from 28,487,837 fine ounces in 1910 to 29,831,111 ounces in 1911. The production of silver from this class of ore increased notably in Alaska, Arizona, Idaho, Montana, Nevada, New Mexico, and Utah, and fell off considerably in Colorado. Under the fifth item is given the quantity of old material, 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 concentrates produced from old tailings, and their gold and silver content, are included under "Concentrates produced." Comparison of the figures for 1910 and 1911 shows that the total quantity of this old material treated increased from 334,637 short tons in 1910 to 412,346 tons in 1911, but that the recovered gold content decreased from 30,323 to 16,259 fine ounces and the silver recovery from 333,809 to 99,475 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 produces 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: Percentage of output of gold and silver by processes in the United States in 1911.


	In this table it is of interest to note that the mills contributed over half the gold output but less than 16 per cent of the silver production, and that the placers, the amalgamation and cyanidation processes, and the smelters mainly supplied the gold production in four nearly equal parts; but that the placers and the amalgamation process contributed very small percentages of the silver output, the chlorination process so small a fraction that it is not given, and the cyanidation process less than 15 per cent—the great bulk of the silver output, or more than 84 per cent, coming from the refining of smeltmg products. The following table shows in greater detail the tonnage treated and output of precious metals by gold and silver mills, by States, in 1911:

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