from
$15.11 to $25.17 per ton. The production of lead-zinc ores, however,
increased from 502,070 to 924,478 short tons, and the percentage of
total output from 1.58 to 2.60 per cent, while the average precious
metal value decreased from $2.67 to $1.80 per ton.
The
production of dry or siliceous ores increased from 1,487,260 short tons
in 1910 to 1,594,404 short tons in 1911 in Alaska, from 1,963,296 to
2,296,347 tons in California, from 115,444 to 122,708 tons in Idaho,
from 1,258,394 to 1,341,495 tons in Nevada, from 86,917 to 135,034 tons
in New Mexico, from 82,064 to 94,353 tons in Oregon, from 1,523,868 to
1,945,770 tons in South Dakota, from 391,568 to 464,229 tons in Utah,
and from 56,860 to 76,239 tons in Washington; the production decreased
from 255,391 to 243,900 tons in Arizona, from 1,957,379 to 1,874,103
tons in Colorado, and from 385,067 to 369,241 tons in Montana. The
great output of this class of ores is notable from Alaska, California,
Colorado, Nevada, and South Dakota, and is mainly from the well-known
Treadwell, Mother Lode and Grass Valley, Cripple Creek, Goldfield and
Tonopah, and Homestake mines, respectively, in these States.
The
output of copper ores increased from 39,365 to 68,975 short tons in
Alaska, from 3,644,495 to 4,274,209 tons in Arizona, from 1,518,000 to
2, 375,000 tons in Michigan, from 2,375,490 to 2,778,325 tons in
Nevada, from 55,220 to 69,305 tons in New Mexico, from 552,796 to
581,974 tons in Tennessee, and from 5,417,558 to 6,121,099 tons in
Utah; and the output decreased from 716,685 to 494,281 tons in
California, from 70,163 to 40,061 tons in Idaho, and from 4,517,709 to
4,332,479 tons in Montana. The large output of Utah and Nevada is
largely from the disseminated deposits, that of Butte (Montana) from
fissure deposits, and that of Michigan from the amygdaloid and
conglomerate deposits of the Keweenaw districts.
The
output of precious-metal bearing lead ores increased from 133,323 to
158,984 short tons in Colorado, and from 329,058 to 393,079 tons in
Utah, but decreased from 1,566,561 to 1,559,724 tons in Idaho in 1911.
The production of argentiferous lead-zinc ores increased from nothing
to 397,354 short tons in Idaho in 1911, and from 231,278 to 280,817
tons in Utah, but decreased from 244,414 to 214,385 tons in Colorado;
and the output of argentiferous zinc ores increased from 82,251 to
110,845 short tons in Colorado, from 34,006 to 51,050 tons in Idaho,
from 169,165 to 225,586 tons in Montana.
The
average extraction value per ton of precious metals derived from dry
and siliceous ores decreased in Alaska from $2.77 in 1910 to $2.66 in
1911, in California from $5.23 to $4.57, in Colorado from $11.65 to
$11, in Idaho from $8.57 to $7.85, in Montana from $9.19 to $8.56, in
Nevada from $19.51 to $18.12, and in Washington from $15.63 to $12.44;
it increased, however, from $8.65 to $9.72 in Arizona, from $9.30 to
$9.70 in New Mexico, from $3.25 to $6.45 in Utah, and from $3.58 to
$3.87 in South Dakota.
The
average extraction value per ton of gold and silver from copper ores in
Arizona was $0.51 in 1911 and $0.59 in 1910, but increased from $1.24
in 1910 to $1.32 in 1911 in Montana, and decreased from $0,117 to
$0.111 in Michigan, from $0.21 to $0.18 in Nevada, and from $0.64 to
$0.60 in Utah. The average value from lead ores increased from $2.27 to
$2.45 in Idaho, and decreased from $12.32 to $9.55 in Utah. In
lead-zinc ores the value decreased from $2.20 to $2.16 in Idaho, and
from $3.33 to $2.93 in Utah.
