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GOLD AND SILVER.
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269
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crude
ore treated in gold and silver mills of the United States increased
from 8,528,596 short tons in 1910 to 9,325,090 tons in 1911 and to
9,367,335 tons in 1912. Increases in tonnage milled are noted
particularly for Alaska, Arizona, Colorado, Nevada, Washington, and
Wyoming, and decreases for California, Idaho, Montana, New Mexico,
Oregon, South Dakota, Texas, Utah, and the southern Appalachians. The
total quantity of gold recovered by mills in 1912 was 2,262,951 fine
ounces (valued at $46,781,349), against 2,440,339 ounces in 1911 and
2,366,322 ounces in 1910. There was increased output from Alaska,
Arizona, California, Oregon, South Dakota, Washington, and the southern
Appalachians, and decreased production from Colorado, Idaho, Montana,
Nevada, New Mexico, and Utah. The total silver recovery in mills was
12,475,279 fine ounces in 1912, against 9,662,545 ounces in 1911 and
8,245,851 ounces in 1910—a marked trend upward. There was increased
silver production in Alaska, California, Nevada (notably, as in 1911,
also), New Mexico, Oregon, and South Dakota, and decreased output from
Arizona, Colorado, Idaho, Montana, Texas, and Utah.
Under
the third item is given the quantity of ore treated for concentration
only, including the large quantities of copper, lead, zinc, and mixed
ores, whose concentrates are smelted primarily for these metals, the
gold and silver being recovered in refining the copper, lead, and zinc.
Examples are the copper ores of the disseminated deposits of Bingham,
Utah, the ores of Butte, Mont., the lead ores of the Coeur d'Alene,
Idaho, and some of the lead-zinc and mixed ores of Leadville, Colo. The
quantity of concentrates produced and the recoverable gold and silver
content, however, as already stated, represent not only the
concentrates from these straight concentrating mills but also those
from gold and silver mills. The concentrates are mainly smelted, as
stated, but are in some cases treated in gold and silver mills by the
processes named. Comparison with corresponding figures published by the
Survey for 1911 shows that the total tonnage treated in straight
concentrating mills (for concentration only) increased from 15,407,515
tons in 1910 to 17,602,315 tons in 1911 and to 22,207,305 tons in 1912,
the greater part of the increase being credited to Arizona, Colorado,
Idaho, Montana, Nevada, New Mexico, and Utah. The total gold and silver
bearing concentrates produced in all classes of mills increased from
2,597,992 tons in 1910 to 2,773,870 tons in 1911 and to 4,303,655 tons
in 1912, the increases being mainly in Alaska, Arizona, California,
Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, and Utah. The
total recoverable gold content of all concentrates aggregated 494,980
fine ounces valued at $10,232,144 in 1912, against 484,971 ounces in
1911 and 475,452 ounces in 1910, the increases being mainly in Alaska,
Colorado, Montana, and Oregon, and the decreases in California, Nevada,
and Utah. The recoverable silver in concentrates produced increased
from 19,949,379 fine ounces in 1910 to 20,794,441 ounces in 1911 and to
22,322,239 ounces in 1912. The increased output was most notable in
Alaska, California, Colorado, Idaho, Montana, Oregon, Utah, and
Washington, and the decreases were mainly in Arizona, Nevada, and New
Mexico.
The
fourth item covers quantity and recoverable precious-metal content of
crude ore shipped direct to smelters from the mines, and in general
includes the'ncher gold, silver, copper, lead, and zinc ores from which
the gold and silver are eventually recovered by refining
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