524 MINERAL RESOURCES, 1920—PART I.
ARIZONA.
Gold.—The
mine production of gold in Arizona in 1920 was $4,786,-122, or $279,709
more than in 1919. Placers contributed only $4,567. The deep mines
produced $4,781,555, of which 65 per cent came from dry or siliceous
ores mined chiefly in Mohave, Yavapai, and Cochise counties; and 33 per
cent was contained in copper ores mined chiefly in Cochise and Yavapai
counties. Mohave County had a gold output of $2,852,141, Cochise County
$919,167, and Yavapai County $659,541. The gold recovered from ores
treated at gold and silver mills represented about 60 per cent of the
total output, against 57 per cent in 1919, and crude ores shipped to
smelters contained nearly 32 per cent. The crude copper ores mined and
smelted directly (without previous concentration) contained an average
gold content of about 55 cents a ton.
Silver.—The
mine production of silver in Arizona increased from 5,266,605 fine
ounces in 1919 to 5,355,303 ounces in 1920. Of this output 3,716,246
ounces came from copper ores, 1,051,982 ounces from dry and siliceous
ores, 521,441 ounces from lead ores, and 65,619 ounces from copper-lead
ores. Cochise County produced 2,314,977 ounces in 1920, of which
1,362,349 ounces came from copper ores and 584,452 ounces from
siliceous ores; and Yavapai County produced 1,555,075 ounces, derived
mainly from copper ores. Bullion recovered from gold and silver ores,
almost all by cyanidation, contained 129,671 ounces of silver,
concentrates 1,125,502 ounces, and crude ore shipped to smelters
4,070,064 ounces.
CALIFORNIA.
Gold.—In
1920 the deep mines produced $7,250,430 (a decrease of $1,412,449), of
which gold-quartz ores yielded 98.7 per cent. California placers in
1920 produced $7,060,613 in gold, or $972,463 less than in 1919. Of the
placer production $6,900,366 was recovered by dredging. The total
dredge production from 1896 to the end of 1920 has been $117,243,197,
and the production by dredges in 1920 was equal to 48 per cent of the
total gold for 1920. The Yuba County dredges, 10 in number, made the
largest output, the value being $3,456,452, a decrease of $729,474.
Sacramento County, with 9 dredges working, made an output of
$1,574,744, a decrease of $137,961. In Butte County (including Oroville
and other districts) 4 dredges produced $441,650 in gold, or $80,046
more than in 1919. Dredges were also operated in Calaveras, Amador,
Stanislaus, Placer, Shasta, Siskiyou, San Joaquin, and Trinity counties.
Five
of the 29 counties reporting mine production of gold each had a yield
of more than $1,000,000 in 1920. Of these Yuba and Sacramento obtained
most of their gold by dredging; Amador and Calaveras are on the Mother
Lode; and Nevada County produced mainly from siliceous ores of the
Grass Valley district. The five Mother Lode counties—Amador, Calaveras,
Eldorado, Mariposa, and Tuolumne—whose output is mainly gold milling
ores, produced $2,558,597 in gold from mill bullion and $862,845 from
concentrates in 1920, against $3,321,121 from mill bullion and
$1,515,317 from concentrates in 1919.
