or
59.39 per cent of the total output, in 1909, to 19,145,677 tons, or
60.36 per cent, in 1910; but the average gold and silver per ton value
dropped from $0.83 in 1909 to $0.74 in 1910. The output of
argentiferous lead ores decreased from 2,243,840 tons, or 7.34 per
cent, with an average precious metal value per ton of $4.65, in 1909,
to 2,081, 545 tons, or 6.56 per cent, with a precious metal value of
$4.44 in 1910. The production of gold and silver bearing zinc ores
increased from 58,173 tons, or 0.19 per cent, in 1909, to 322,008 tons,
or 1.02 per cent, in 1910, but decreased in average precious metal
value per ton from $3.68 to $1.46. The output of copper-lead and
copper-lead-zinc ores decreased from 32,193 tons, or 0.11 per cent,
with an average precious metal value per ton of $20.18, in 1909, to
20,318 tons, or 0.07 per cent, and a gold and silver value of $15.11 in
1910. The production of lead-zinc ores, on the other hand, increased
from 322,477 tons, or 1.05 per cent, with a gold and silver value of
$2.42, in 1909, to 502,070 tons, or 1.58 per cent, with a value of
$2.67 in 1910.
The
production of dry or siliceous ores increased from 237,078 tons in 1909
to 255,391 tons in 1910 in Arizona; from 1,749,112 to 1,957,379 tons in
Colorado; from 1,229,651 to 1,258,394 tons in Nevada; and from 358,116
to 391,568 tons in Utah. The output of this class of ore decreased from
1,496,361 tons to 1,487,260 tons in Alaska; from 2,195,741 to 1,963,296
tons in California; from 1,702,266 to 1,523,868 tons in South Dakota;
from 185,734 to 115,444 tons in Idaho, and from 416,329 to 385,067 tons
in Montana. The great output of this class of ore is notable in Alaska,
California, Colorado, Nevada, and South Dakota, and is mainly from the
famous Treadwell, Mother Lode and Grass Valley, Cripple Creek,
Goldfield and Tonopah, and Homestake mines, respectively, in these
States.
The
production of copper ores increased from 1,670,457 tons in 1909 to
2,375,490 tons in 1910 in Nevada, and from 4,216,226 to 5,417,558 tons
in Utah. The output decreased in Arizona from 3,741,713 tons to
3,644,495 tons, in California from 840,358 to 716,685 tons, in Montana
from 4,965,001 to 4,517,709 tons, and in Tennessee from 576,680 to
552,796 tons. The great output from 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 lodes of the
Keweenaw district.
The
output of precious metal bearing lead ores increased from 1,466,592
tons to 1,566,561 tons in Idaho, but decreased from 174,483 tons to
133,323 tons in Colorado, and from 480,248 to 329,058 tons in Utah. The
production of argentiferous lead-zinc ores increased from 221,192 tons
to 244,414 tons in Colorado and from 60,275 to 231,278 tons in Utah.
The output of argentiferous zinc ores also increased from 5,014 tons to
82,251 tons in Colorado and from 34,463 to 169,165 tons in Montana.
The
average extraction value of precious metals derived from dry or
siliceous ores increased in Arizona from $7.31 to $8.65 per ton; in
California from $4.86 to $5.23; in Idaho from $7.86 to $8.57; in
Montana from $8.11 to $9.19; in Nevada from $16.58 to $19.51 and in
New Mexico from $7.99 to $9.30. These are notable changes for the
better and indicate in part at least improved metallurgical methods.
Decreased average extraction is noted in Colorado from $13.41 to $11.65
per ton and in South Dakota from $3.92 to $3.58 per ton, chiefly due
probably to changes in grade of ore treated. In Alaska the recovery was
$2.76 per ton in 1909 and $2.77 in 1910. 21235°—m r 1910, pt 1------10
