748 MINERAL, RESOURCES, 1918—PART I.
$9,810,000
in 1917. Twenty-eight dredges produced $1,425,000 of the placer gold,
which was $1,075,000 less than the yield from dredging m 1917.
Of
the productive gold lode mines, 6 were in southeastern Alaska, 3 on
Prince William Sound, 4 in Kenai Peninsula, 5 in Willow Creek district,
and 6 in Fairbanks district. The 6 deep gold mines in southeastern
Alaska yielded more than 90 per cent of the gold derived from siliceous
ores.
The
2,095,573 tons of siliceous ores treated in 1918 yielded an average of
$1.70 in gold and silver a ton, and the 722,047 tons of copper ore
contained $1.07 in gold and silver a ton and had a copper content of
4.8 per cent.
Nearly
37 per cent of the total output of gold in Alaska came from gold lode
mines in 1918, against 31 per cent in 1917, 34 per cent in
1916, 36
per cent in 1915, 31 per cent in 1914, 31 per cent in 1913, and 29 per
cent in 1912. The 727 placers operated in 1918 yielded approximately
4,931,000 cubic yards of auriferous gravel, of which the dredges
handled about 2,490,000 cubic yards and made an average recovery of 57
cents a cubic yard in 1918, against 68 cents a yard in
1917, 69 cents a yard in 1916, 51 cents a yard in 1915, and 53 cents a yard in 1914.
The estimated total recovery of gold bv dredging for the period 1903-1918, inclusive, is $19,035,000.
No important new placer-bearing areas were reported in 1918.
Silver.—The
mine production of silver in Alaska in 1918 was 847,789 fine ounces,
against 1,239,150 ounces in 1917. The copper mines produced 719,391
ounces—a decrease of 321,762 ounces; the siliceous ores yielded 90,064
ounces in 1918, against 133,587 ounces in 1917; and the placers yielded
38,334 ounces in 1918, against 64,410 ounces in 1917.
ARIZONA.
Gold.—The
mine production of gold in Arizona in 1918 was, $5,435,027, which was
$366,834, or about 7 per cent, more than in 1917. Placers contributed
only $4,234, which came from small mines in Yuma, Pima, Maricopa, and
Yavapai counties. The deep mines produced $5,430,793, of which 57 per
cent came from dry or siliceous ores mined chiefly in Mohave, Yavapai,
and Cochise counties, and 41 per cent was contained in copper ores
mined chiefly in Cochise and Yavapai counties. Mohave County had a gold
output of $2,798,903, an increase of more than $335,000, Cochise County
produced $1,108,685, and Yavapai County $1,117,701. The gold recovered
from ores treated at gold and silver mills represented 53 per cent of
the total output, against 49 per cent in 1917, and crude ores shipped
to smelters contained nearly 39 per cent. The crude copper ores mined
and smelted directly (without previous concentration) contained an
average gold content of 49 cents a ton.
Silver.—The
mine production of silver in Arizona decreased from 6,983,913 fine
ounces in 1917 to 6,686,152 ounces in 1918. Of this production
5,347,618 ounces came from copper ores, 917,973 ounces from dry or
siliceous ores, 362,182 ounces from lead ores, 36,208 ounces from
lead-zinc ores, and smaller quantities from zinc, copper-zinc, and
copper-lead ores. Cochise County produced 2,315,518 ounces in 1918, of
which 1,693,598 ounces came from copper ores
