in
1910 is recorded from Arizona and Washington and especially from
Nevada, and there was an increase also from New Mexico. Decreased
p
roduction of gold from
these ores was reported in 1910 from Alaska, California, Colorado,
Georgia, Idaho, Montana, Oregon, South Dakota, and Utah. The falling
off was notable in South Dakota.
The
siliceous ores are in part free-milling, as in Alaska, California, and
Oregon; in part both amalgamating and concentrating, as in many States;
and in smaller part straight concentrating ores, as in parts of
Colorado and Arizona, or smelting ores. Tailings both from old dumps
and from present milling are now largely reworked by concentration and
cyanidation. The all-sliming and cyanidation method is of increasing
importance, and crushing is now largely by tube as well as by stamp and
rotary mills. The loss in tailings from gold mills is constantly being
reduced, and the most serious present loss is probably in tailings from
concentration plants. The chlori-nation process is of decreasing
relative importance. Smelting is mainly of concentrates, and of
siliceous and pyritic ores which are also valuable as fluxes. It is
hoped that some exact figures of relative gold production in the
United States by amalgamation, cyanidation, and chlorination may be
given in forthcoming reports.
Copper ores.—The
production of gold from copper ores in 1910 was $5,471,200, against
$5,631,885 in 1909. Increases in 1910 in gold output from this source
are noted from Alaska, Arizona, Nevada, and New Mexico, and decreases
from California, Colorado, Idaho, Montana, and Utah. The States leading
in production of gold from copper ores, in order of rank, are Utah and
Arizona (each of which produced over $1,000,000 in gold from this
source), and California, Montana, and Nevada. The Utah copper ores are
notable in this respect. The gold is recovered by electrolytic refining
of blister copper obtained in smelting the ores and concentrates.
Lead ores.—The
production of gold from lead ores was $1,122,090 in 1910, against
$1,577,173 in 1909. The Utah lead ores rank first in total yield of
gold, followed by those from Colorado. The remainder of the gold
output from this source is chiefly from Montana, Nevada, Idaho,
Arizona, and California, in order named. Increases are noted from
California, Idaho, and Montana, and decreases from the other States
named.
Lead-zinc ores.—Production
of gold from lead-zinc ores was $277,541 in 1910, against $188,056 in
1909, and is almost wholly from Colorado and Utah, in both of which
States the output from this source increased in 1910.
Zinc ores and mixed ores.—The
total gold production from zinc ores was $61,036 in 1910, against
$50,582 in 1909; and from copper-lead and copper-lead-zinc ores it was
$17,500 in 1910, against $363,765 in 1909. The marked decrease from the
mixed ores was from Arizona and Colorado.
DISTRIBUTION OF SILVER PRODUCTION OF 1910.
The
mine production of silver from dry or siliceous ores, copper ores, and
lead ores combined was 94.06 per cent of the total output in 1910,
against 96.24 per cent in 1909. The production from dry or siliceous
ores increased from 34.59 per cent to 40.15 per cent of the total, but
the output from copper ores decreased from 31.93 per cent to 27.82 per
cent, and that from lead ores from 29.72 per cent to
