ounces.
A decrease of 2,800,000 ounces was reported from Montana. Utah showed
an increase of over 700,000 ounces, due to the mining' of an increased
tonnage of the rich Tintic ores. The output of Arizona, which was about
300,000 ounces less than that of 1906, is mainly derived from the
United Verde copper district.
Lead ores.—The
total of silver derived from lead ores was 17,318,811 ounces. Utah was
the most important State, with a production of 7,300,010 ounces from
Park City, Tintic, and Bingham ores. Idaho was next, with somewhat over
6,800,000 ounces, a decrease of about 800,000 ounces from 1906.
Colorado was third in rank, having yielded 2,357,901 ounces from these
kinds of ores. No other State even approached Utah, Idaho, and Colorado
in this respect. Montana was formerly an important producer, but now
yields only a few hundred thousand ounces.
Oxidized
lead ores are still furnished by Tintic, Utah; Aspen, Colo., and other
places in Colorado, Arizona, New Mexico, and Nevada.
Copper-lead ores.—In
the report for 1906 a large output of silver from copper-lead ores was
credited to Utah, but it has been found possible in 1907 to distribute
most of this output among the lead ores and copper ores. These ores are
mined in Tintic, and the same mine often produces both classes of ores.
Aside from this district the mixed copper-lead ores are of small
importance.
Zinc ores and zinc-lead ores.—The
zinc ores proper contribute only a small amount of silver; such ores
were shipped from Colorado and Utah. The zinc-lead ores are produced
chiefly in Colorado, and in 1907 yielded about 1,500,000 ounces. They
are usually concentrated into zinc and lead products. The decrease in
the activity of zinc mining found expression in a greatly reduced
yield. As usual, Colorado contributed the greatest output, but smaller
quantities were also mined in Idaho, Utah, Nevada, California, and New
Mexico.
