ARIZONA.
Gold.—The
mine production of gold in Arizona in 1915 was $4,166,025, which was
$13,130 less than in 1914. Placers contributed only $35,248, most of
which came from small mines in Yuma and Yavapai counties. The deep
mines produced $4,130,777, of which 52 per cent came from dry or
siliceous ores mined chiefly in Mohave, Maricopa, and Cochise counties,
and 43 per cent was contained in copper ores mined chiefly in Cochise
and Yavapai counties. Mohave County had a gold output of $1,626,437,
Cochise County $1,223,882, and Yavapai County $791,884. The gold
recovered from ores treated at gold and silver mills represented 46 per
cent of the total output and crude ores shipped to smelters contained
nearly 44 per cent. The crude copper ores mined and smelted directly
(without previous concentration) contained an average gold content of
65 cents a ton.
Silver.—The
mine production of silver increased from 4,377,994 fine ounces in 1914
to 5,649,020 ounces in 1915. Of this production 4,010,510 ounces came
from copper ores, 994,184 ounces from dry or siliceous ores, 393,444
ounces from lead ores, 172,103 ounces from lead-zinc ores, and smaller
quantities from zinc and copper-lead ores. Cochise County produced
3,034,714 ounces in 1915, of which 1,842,559 ounces came from copper
ores and 865,215 ounces from siliceous ores. The silver output of
Yavapai County, which increased from 786,917 ounces in 1914 to
1,343,363 ounces in 1915 was nearly all derived from copper ores.
Bullion recovered from gold and silver ores, almost all by cyanidation,
yielded 741,578 ounces of silver. Concentrates contained 910,138 ounces
and crude ore shipped to smelters contained 3,945,730 ounces, or more
than 69 per cent of the total output of silver.
CALIFORNIA.
Gold.—The
mine production of gold in California in 1915, $22,442,296, was the
largest in 33 years, and with the exception of 1883 it was larger than
for any year since 1864. The increased yield of $1,788,800 was due to
deep-mining operations.
In
1915 the deep mines produced $13,833,679 (an increase of $2,261,032),
of which gold-quartz ores yielded 96.2 per cent and copper ores 3.5
per cent. California placers in 1915 yielded $8,608,617 in gold, or
$472,232 less than in 1914. Of the placer production $420,770 was
recovered by hydraulic mining, $272,955 by drift mining, $118,427 by
sluicing, and $7,796,465 by dredging. The total dredge production from
1898 to the end of 1915 has been $79,104,231 and the yield of gold by
dredges was equal to 35 per cent of the total yield of gold for 1915.
The Yuba County dredges, 12 in number, made the largest output of gold,
the value being $2,676,090, a decrease of $79,644. Sacramento Countv,
with 11 dredges working, made an output of $2,129,787, a decrease of
$31,866. In Butte County (including Oroville and other districts) 17
dredges produced $1,491,066 in gold, or $146,959 less than in 1914.
Dredges were also operated in Calaveras, Eldorado, Merced, Stanislaus,
Placer, Shasta, Siskiyou, and Trinity counties.
