DRY AND SILICEOUS ORES.
In
1914 dry and siliceous ores, including true gold, gold-silver, and
silver ores, and precious metal ores not classed as primarily copper,
lead, zinc, or mixed ores, produced $60,793,236 in gold, against
$59,222,751 in 1913, or more than 66 per cent of the total output in
each year. The largest producers from this class of ore are in order of
rank: Colorado, California, Nevada, South Dakota, and Alaska.
The
siliceous ores are in part free-milling (amalgamating), as in Alaska,
California, and Oregon; in part both amalgamating and concentrating, as
in many States; hi smaller part simply concentrating ores, as in parts
of Colorado and Arizona; in increasing part an-sliming and cyaniding
ores; and finally in some part smelting ores. Tailings both from old
dumps and from present milling are largely reworked by concentration
and subsequent cyanidation.
The
loss in tailings from gold mills is being constantly cut down, and the
most serious present loss is in tailings from concentrating plants. The
chlorination process is of decreasing relative importance. Smelting is
mainly of concentrates and of siliceous and pyritic ores, which are
also valuable as fluxes. Exact figures of relative output by methods
will appear in detail by States in another table.
COPPER ORES.
The
production of gold as a by-product of the smelting of copper ores sold
or treated m 1914 was $5,474,559, against $5,697,855 in
1913,
a decrease from 6.4 per cent of the total gold yield in 1913 to 6 per
cent in 1914. The largest production was in Utah, followed by Arizona,
Nevada, and Montana, in the order given.
LEAD ORES.
The
production of gold from refining lead bullion from lead ores sold or
treated in 1914, chiefly from Utah and Colorado, was $1,540,348,
against $1,527,246 in 1913, or 1.7 per cent of the total domestic
output of gold in each year.
LEAD-ZINC, ZINC, AND OTHER ORES.
The
production of gold from lead-zinc ores was $360,746 in 1914, against
$316,512 in 1913; from zinc ores $39,548 in 1914, against $18,528 in
1913; and from copper-lead and copper-lead-zinc ores $11,323 in 1914,
against $97,094 in 1913.
DISTRIBUTION" OF PRODUCTION OF SILVER IN 1914, BY SOURCES.
The
mine production of silver from (1) dry or siliceous ores, (2) copper
ores, and (3) lead ores combined, was 89 per cent of the total output
against 91 per cent in 1913, 93 per cent in 1912, and 94 per cent in
1911. The output from lead-zinc ores increased from 7.5 per cent in
1913 to a little over 10 per cent hi 1914.
The output from dry and siliceous ores increased 0.6 per cent in
1914,
and that from lead ores increased 1.5 per cent, but that from copper
ores decreased 4.3 per cent. The output from placers, zinc ores,
copper-lead, and copper-lead-zinc ores is relatively insignificant.
The following table shows the sources of domestic production of silver by classes of ore, by States:
