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250
MINERAL RESOURCES.
Distribution of production of gold and silver in 1911, by methods of treatment, by States.
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The
first item consists of all classes of ores, tailings, and slag
producing gold and silver in the United States in 1911. The grand
total shows that this tonnage increased from 30,287,175 short tons in
1910 to 32,928,522 short tons in 1911. This takes no account of placer
gravel, but represents product of deep mines only. The largest
increase in quantity in 1911 was in Utah, followed by considerable
increases in Arizona, South Dakota, and Nevada. The quantity decreased
in Colorado and Montana.
In
reference to the second item, many gold and silver mills employ
concentrating apparatus, and the concentrates resulting are combined
with those from straight concentrating mills in the column of the table
"Concentrates produced." The gold and silver recovery under this item
is mainly by amalgamation and cyanidation, as shown in detail in the
last table of this report. The total quantity of crude
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