the
copper or lead bullion that collects the precious metals in the
smelting. The total quantity shipped of this class of ore decreased
from 6,016,425 short tons in 1910 to 5,588,771 tons in 1911, but
increased to 6,543,436 tons in 1912. The increases for 1912 were mainly
in Alaska, Arizona, Colorado, Idaho, Montana, Nevada, and New Mexico;
and the decreases were chiefly in California and Utah. The tonnages are
notably large in Arizona and Utah and the bulk of the precious metal
bearing ores of the Eastern States are smelted crude. The total gold
output from crude ores smelted decreased from 623,272 fine ounces in
1910 to 611,344 ounces in 1911 and to 578,391 ounces, valued at
$11,956,403, in 1912, the decreases being chiefly in California, Idaho,
Montana, Nevada, Utah, and Washington, and the increases in Alaska,
Arizona, Colorado, New Mexico, Utah, and Washington. The total
recoverable silver output in crude ores shipped to smelters increased
from 28,487,837 fine ounces in 1910 to 29,831,111 ounces in 1911 and
decreased to 29,729,092 ounces in 1912. The increases in 1912 were
chiefly in Alaska, Arizona, Colorado, New Mexico, Utah, and Washington,
and the decreases in California, Idaho, Montana, Nevada, Oregon, and
South Dakota.
Under
the fifth item is given the quantity of old materials, 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 Colorado tailings
treated are included in the first column of the table with crude ore.
The concentrates produced from old tailings, and their gold and silver
content, are included under "Concentrates produced." Comparison of the
figures for 1911 and 1912 shows that the total quantity of this old
material treated (excluding that in Colorado) increased from 412,346
short tons in 1911 to 476,730 tons in 1912, but that the recovered gold
content decreased from 16,259 to 15,614 fine ounces and that the silver
recovery increased from 99,475 to 775,198 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 is reported to produce 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 and 1912:
