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GOLD AND SILVER.
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253
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PLACERS.
The
total value of the gold placer production was $23,019,633 in 1912,
against $23,415,168 in 1911. These figures represent 24.94 per cent of
the total domestic gold output for 1912 and 24.17 per cent of that for
1911. The placer production of Alaska was $11,990,000 in 1912, against
$12,540,000 in 1911, and that of California was $8,645,663 in 1912,
against $8,986,527 in 1912.
Dredging
supplied $11,218,804 in 1912 and $10,311,589 in 1911. Of this
California produced $7,429,955 in 1912, against $7,666,461 in 1911. The
total production of gold by dredging in California to the end of 1912
was $55,415,191. In 1912 Alaska produced $2,200,000 by dredging,
against $1,500,000 in 1911 and $800,000 in 1910. The gold output by
dredges and the number of boats producing in 1912 and 1911 is shown in
the following table:
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The
remainder of the placer production is chiefly from drift mining (which
is of decreasing importance in Alaska in frozen ground at no great
depth, but of continued importance in California in ancient buried
river channels, often at considerable depth) and from hydraulic and
sluicing placers. In California, especially, hydraulic mining has been
of much importance in the past and a special branch of the industry in
itself, but restrictive laws relative to the debris and to disturbance
of navigable streams have in recent years greatly confined mining
activity of this kind. Finally, there is also a small annual output of
gold from dry placers of the Southwest, and a considerable production
of gold and platinum from ocean beach mining in California and Oregon.
The following notes have been taken from the Survey report on precious
and semiprecious metals in California and Oregon, in 1912, by Charles
G. Yale, published in volume 1 of Mineral Resources of the United
States for that year:
BEACH MINING IN CALIFORNIA AND OREGON.
By Charles G. Yale.
California.—A
form of gold mining somewhat peculiar to the Pacific coast, and a
source of gold production in California, is mining the heavy black sand
of the ocean beaches, especially near the mouths of rivers draining
areas which carry auriferous gravels. These beaches are worked
intermittently, more particularly after winter
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