increase
over the output of 1910) to 7,085,596 ounces in 1912, the production
from Utah increased from 6,083,877 to 6,212,219 ounces, and that from
Colorado from 1,265,594 to 1,470,930 ounces. Fourth in rank was Nevada,
with an increase to 841,733 ounces in 1912 from 186,485 ounces in 1911,
and fifth was Arizona with a decrease to 599,110 from 635,363 ounces.
The output in Idaho has been mainly from the Coeur d'Alene, 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 ores are still mined at Tintic,
Aspen, and a few other camps.
ZINC, LEAD-ZINC, AND MIXED ORES.
Argentiferous
zinc ores supplied 664,421 fine ounces of silver in 1912, against
630,573 ounces in 1911, the output and increase being mainly from
Montana and Colorado, where the zinc-mining industry has been making
rapid strides, especially at Butte.
Lead-zinc
ores furnished 2,810,939 fine ounces of silver in 1912, against
2,460,152 ounces in 1911. The output and increase are mainly from Utah,
which produced 1,425,663 ounces from this source in 1912 against
1,358,311 ounces in 1911, although Idaho and Colorado produced
respectively 513,286 and 594,427 ounces in 1912, against 510,667 and
476,049 ounces in 1911.
Copper-lead
and copper-lead-zinc ores in 1912 yielded 654,596 ounces of silver,
against 285,006 ounces in 1911. The production was mainly from Colorado
and Utah (where there were large increases in 1912), and from Montana,
where there was decreased output.
DISTRIBUTION OF PRODUCTION OF GOLD AND SILVER, BY METHODS OF TREATMENT.
In
the Survey report on gold and silver for 1910 figures were first
published showing the distribution of output by methods of treatment.
In
the following table a summary is given of the distribution of the gold
and silver production of the United States in 1912, showing—
1. Total crude ore, tailings, and slags sold or treated in 1912.
2. Crude ore treated in gold and silver mills.
3. Crude ore concentrated, with resulting concentrates.
4. Crude ore shipped to smelters.
5. Old tailings and slags treated.
The last four include recoverable gold and silver content in fine ounces.
