Ch. 1: Gold and Silver in 1912

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GOLD AND SILVER.
271
The mills contributed over half the gold output in 1911 and 1912 and increased the relative output of silver from 15.7 per cent of the total in 1911 to 19 per cent in 1912. The placers, the amalgamation and the cyanidation processes, and the smelters supplied practically all the gold production in nearly equal parts, the recovery of gold by the chlorination process having declined from 3.8 per cent of the total output of gold m 1911 to 0.4 per cent in 1912. The placers and amalgamation processes contribute very small percentages of the total silver production. The bulk of the output remains from the smelters treating crude ore, concentrates, and other material, the
E percentage of total output of silver from this source having declined, however, from 84 per cent in 1911 to 80.8 per cent in 1912. This decline is explained by the corresponding rise in relative recovery of silver by cyanidation, from 15.7 per cent of the total output in 1911 to 19 per cent in 1912.
The following table shows in greater detail the tonnage treated and output of precious metals by gold and silver mills, by States, in 1912:
Quantity of ore treated at gold and silver mills in 1912, giving recoveries by amalgamation and cyanidation and percentage of each to gold and silver recovered from all sources.
Figures corresponding to those in this table were collected and compiled for the United States for the first time in 1911 by the Survey, and comparison for two years for the first time can there­fore now be made.
The total quantity of crude ore and old tailings treated in gold and silver mills in 1912 was 9,677,360 short tons, against 9,670,483 tons in 1911.
The great bulk of the ore treated, as shown, was milled in Cali­fornia, South Dakota, Alaska, Colorado, and Nevada, and here the
Ch. 1: Gold and Silver in 1912 Page of 93 Ch. 1: Gold and Silver in 1912
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US Geol. Surv. 1912. Gemstones, Metals.
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