|
236
|
MINERAL RESOURCES.
|
||
|
|
|||
|
number
of deep mines increased by 116 and the number of placers decreased by
161. In 1909 the number of deep mines increased by 319 and the number
of placer mines decreased by 412. For the last six years the number of
producing mines has been as follows:
Number of mines producing gold and silver, 1906-1911.
|
|||
|
|
|||
|
|
|||
|
|
|||
|
The
figures show a general decrease in number of placer mines, but a steady
increase in deep mines. The enumeration of placer mines presents
certain difficulties, as noted above, and it has been especially
difficult in Alaska in earlier years.
In
Alaska the estimate for producing placer mines was 650 in 1910 and 740
for 1911, and there were 19 deep mines producing in 1910 and 26 in
1911. In Arizona the placers decreased from 44 in 1910 to 42 in 1911,
but the number of deep mines increased from 329 to 355. In California
the number of placers was 564 in 1910 and 585 in 1911 and the number of
deep mines was 515 in 1910 and 596 in 1911. In Colorado the number of
placers decreased from 42 to 39, but the deep mines increased from 856
to 861. In Idaho the number of producing placers was 262 in 1910 and
217 in 1911 and the number of deep mines 155 in 1910 and 157 in 1911.
In Montana the placers increased from 155 to 180 and the deep mines
from 423 to 530. In Nevada the
E
lacers increased from
68 to 72 and.the deep mines from 540 to 589. a New Mexico the placers
decreased from 23 to 20 and the number of deep mines was 85 in each
year. In Oregon the placers increased from 116 to 136, but the number
of deep mines fell off from 64 to 40. In South Dakota the placers
increased from 8 to 17 and the deep mines from 18 to 20. In Utah the
number of productive placers was 8 in each year, but the number of deep
mines increased from 175 in 1910 to 200 in 1911. In Washington the
number of placers increased from 21 to 24, but the deep mines fell off
from 55 to 36. In the Central States there are no placers and the
number of deep mines remained in 1911 as in 1910. In the Eastern States
the total number of placers decreased from 61 to 57 and the total
number of mines producing gold and silver was 39 in each year.
ORE PRODUCTION, CLASSIFICATION, AND AVERAGE VALTJES.
The
best index of deep mining is, of course, the tonnage, content, and
value of ore mined, rather than the number of mines or of operators.
In the next following table is given the ore production, bv classes of
ore and by States and Territories, of mines producing gold and silver
and the average extraction value of precious metals per ton.
The
classification adopted is necessarily arbitrary in part. An ore is
generally understood to be worked at a profit for one or more metals.
|
|||
|
|
|||