districts,
in the Iditarod-Innoko region, and on Seward Peninsula; to shortage of
labor in some places; and to the approaching exhaustion of the bonanza
deposits of the Fairbanks district. Shortage of auriferous gravels is
not imminent, but only of those that can be mined at present high costs
and under other present difficulties. New areas of placer ground
available for future dredging under better transportation conditions
are being discovered and the installation of dredges in the accessible
portions of the Seward Peninsula has been continued.
In
1913 about 31.6 per cent of the Alaskan gold output came from lode
mines, against 29 per cent in 1912 and 24 per cent in 1911. The trend
is obviously toward increased relative production from these mines as
compared with the placers, and with the completion of the great
development work on the vast low grade deposits of southeastern Alaska
the gold output from this region should greatly increase. Increase of
gold yield from enlarged dredging operations may confidently be
expected also, however, and future decreases for some time to come will
probably be in the more primitive methods of placer mining.
The
operating mines of southeastern Alaska, 7 lode gold mines, 4 placers,
and 3 copper mines, produced $4,229,648 in gold in 1913, the bulk of
which was from the famous Treadwell group of the Juneau region.
Development of the vast gold deposits of the adjoining Alaska-Gastineau
and Alaska-Juneau mines bids fair to make these, with the
Alaska-Treadwell, the center of one of the great gold-mining districts
of the world.
Thirty-six
gold dredges were productive in Alaska in 1913, of which 31 were on the
Seward Peninsula. Altogether the dredges treated about 4,100,000 cubic
yards of gravel and produced about $2,200,000 in gold. It is estimated
that about 700 placer mines in all were in operation and that a total
of about 6,800,000 cubic yards of gravel were handled with an average
recovery of $1.57 per yard, against 7,050,000 yards in 1912 with an
average recovery of $1.70 per yard.
Stiver.—The
production of silver in Alaska in 1913 was 362,563 fine ounces, against
515,186 ounces in 1912. Of the total output 273,179 ounces came from
copper ores, 58,487 ounces from placer gold, and 30,897 ounces from
siliceous gold ores.
ARIZONA.
Gold.—The
recoverable output of gold from Arizona mines in 1913 was $4,023,911,
against $3,762,210 in 1912, an increase of $261,701. This was the
largest recorded production from Arizona to date. Of the output for
1913 $30,691 came from placers, principally in Yavapai, Yuma, and Pima
counties, $2,558,426 came from dry and siliceous ores, chiefly from the
gold-milling ores of the San Francisco district of Mohave County and
the Vulture district of Maricopa County, and $1,332,038 was derived
from copper ores, mainly from the Warren (Bisbee) district of Cochise
County and the Verde district of Yavapai County. Mohave County again
led in gold production followed by Cochise, Maricopa, and Yavapai, in
order. By the amalgamation process $302,120 in gold was produced in
Arizona in 1913, against $236,345 in 1912, and by the cyanidation
process, $2,007,704, against
