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GOLD AND SILVER.
131
General statement.—The
totals in this table indicate that siliceous or dry ores, which in
general may be considered as gold ores proper, furnished about 62 per
cent of the whole production, and that placers yielded approximately 26
per cent. The base-metal ores contributed between 9 and 10 per cent of
the total output, although the tonnage of these ores, as shown in a
previous table, was exceedingly heavy. The copper ores yielded most of
the gold from this source, while the lead ores only gave a small
percentage, and the gold from zinc ores was insignificant in amount.
Compared
with 1906, the placer gold decreased by about $2,400,000. The gold from
siliceous ores decreased approximately $7,000,000. Copper ores yielded
almost exactly the same amount of gold as in 1906. The gold from lead
ores and copper-lead ores increased slightly. There was, on the other
hand, a considerable decrease in the always small quantity of gold
obtained from lead-zinc ores.
Placers.—The
placer gold obtained in 1907 aggregated 1,192,890 fine ounces,
equivalent to $25,659,225, while in 1906 the quantity was 1,328,361
fine ounces, equivalent to $27,459,653. The great advance in the yield
of placer gold which took place in 1905 and 1906 was thus followed by a
considerable setback in 1907. Alaska led in the production, with about
$16,000,000, and was followed by California, which yielded about
$6,840,000. In all the other States the production is very materially
smaller. Montana, like Alaska and California, reported a considerably
reduced yield, amounting to about $350,000. Idaho remained at about the
same figures, and Oregon contributed $331,000, a somewhat decreased
output as compared with 1906. Many of the other States showed an
increase in their small production. Among these are Arizona, Colorado
(in which State the output was almost doubled in 1907), Nevada, Utah,
and Washington.
Gold
dredging has developed into a most important industry in California.
The yield from this branch of mining in that State in recent years has
been as follows: 1904, $2,187,038; 1905, $3,276,143; 1906, $5,098,359;
1907, $5,065,437. It is not unlikely that 1908 will show an increase
over 1907. Fifty-seven dredges were operating in California. The total
yield from all dredging operations, outside of California, was only
$571,659, divided between Alaska, Colorado, Georgia, Idaho, New Mexico,
Montana, and Oregon. Details can not well be given without disclosing
individual production. Seventy-nine dredge boats were in operation as
follows: Alaska, 4; California, 57; Colorado, 3; Georgia, 2; Idaho, 6;
New Mexico, 1; Montana, 4; and Oregon, 2. No gold was reported from
dredging along Snake River.
Drift
mining in frozen ground has yielded most of the gold from the Lower
Tanana in Alaska, and a large part of the gold from the Seward
Peninsula is also obtained by this method of mining. In California
drift mining still remains an important branch, but the yield is
declining, and was only about $565,575 in 1907.
The
remaining placer gold is won by the hydraulic method or by surface
sluicing work, which is practiced in all of the placer States. A very
small amount of placer gold is derived from dry washing in New Mexico
and Arizona.
Dry and siliceous ores.—The States which yielded over 100,000 ounces from this source rank as follows: Colorado, Nevada, California,
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