The
output from Idaho increased from 5,692,906 ounces in 1909 to 6,479,636
ounces in 1910, while that from Utah decreased from 8,314,766 to
6,423,523 ounces, that from Nevada from 1,415,416 to 583,282 ounces,
and that from Colorado from 1,127,589 to 1,050,611 ounces. The output
in Idaho is mainly from the Coeur d'Alenes, that in Utah from the Park
City and Tintic districts, and that in Colorado from Aspen and
Leadville. Although much of this silver production is from
argentiferous galena, oxidized silver-lead ores are still mined at
Tintic, Aspen, and a few other camps.
Zinc, lead-zinc, and mixed ores.—Argentiferous
zinc ores supplied 755,369 fine ounces of silver in 1910, as against
313,948 ounces in 1909 and 37,605 ounces in 1908, the output and the
increase being mainly from the Butte district of Montana, where the
zinc mining industry has been making rapid strides.
Lead-zinc
ores furnished 1,968,311 ounces of silver in 1910, as against 1,141,434
ounces in 1909. Production from this source increased from 399,396
ounces to 1,228,398 ounces in Utah, and from 15,684 to 54,550 ounces in
New Mexico, but decreased slightly in Colorado and ceased entirely in
Idaho.
Copper-lead
and copper-lead-zinc ores supplied 535,987 fine ounces of silver in
1910, as against 549,923 ounces in 1909. The production is mainly from
Utah, Colorado, and Montana, the increase being large in Utah and the
decrease large in Colorado and Montana in 1910.
DISTRIBUTION OF PRODUCTION OF GOLD AND SILVER BY METHODS OF TREATMENT.
An
attempt is made in the following table to summarize the distribution
of the gold and silver production of the United States (1) by tonnage
of ore treated in gold and silver mills; (2) by tonnage of ore
concentrated, with resulting tonnage of concentrates produced; (3) by
tonnage of ore smelted crude; and (4) by tonnage of old tailings or
slags treated—all with recoverable gold and silver content in fine
ounces, and by States.
In
reference to the first item it should be remembered that many gold and
silver mills employ concentrating apparatus, and the concentrates
resulting, those from California, for example, are combined with those
from straight concentrating mills in the column "concentrates
produced." The gold and silver recovery under this item is mainly by
amalgamation and cyanidation. Data for exact figures for recovery
separately by amalgamation, cyanidation, and chlorina-tion are in
prospect for a forthcoming report.
Under
the second item is given the tonnage 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 of which are 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'Alenes,
Idaho, and some of the lead-zinc and mixed ores of Leadville, Colo. The
tonnage of concentrates produced and the recoverable metal, as stated
above, 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.
