The
first item consists of all classes of ores, failings, and slags from
which gold and silver was produced in 1914. The grand total is
40,679,262 short tons in 1914, against 43,984,220 tons in 1913. This
takes no account of placer gravel but represents output of mines
producing ore only. The greatest output was from Utah, Arizona,
Montana, and Nevada, all notable for large yield of copper ores.
In
reference to the second item many gold and silver mills employ
concentrating apparatus, and the concentrates produced are combined in
the table with those from straight concentrating mills under the
heading "concentrates produced." The gold and silver recovery under
this item is mainly by amalgamation and cyanidation, as is shown in
detad in the last table of this report. The total quantity of crude ore
treated in gold and silver mills in 1914 was 9,761,336 short tons,
against 9,261,899 tons in 1913, and was the largest quantity so treated
since these figures were first compded by the Survey for 1910. The
reatest tonnages milled were in South Dakota, California, Alaska,
olorado, and Nevada. The total recovery of gold from the mills was
2,224,518 fine ounces in 1914, against 2,179,348 ounces in 1913, and
the production was as usual, chiefly from Colorado, Nevada. California,
and South Dakota, in the order named. The total silver recovery in
mills was 15,656,831 fine ounces against 14,492,424 ounces in 1913, and
came very largely from Nevada—from Tonopan* and Gold-field chiefly, but
also in considerable part from New Mexico, Colorado, and Arizona.
Under
the third item is given the quantity of ore treated by concentration
only, including the large quantities of copper, lead, zinc, and mixed
ores, whose concentrates are smelted primarily for these metals, the
gold and sdver being recovered in refining the copper and
