closing
of the Trade Dollar mill, in March, 1910. Placers in Idaho supplied
$242,546 in gold, of which $91,247 was recovered by 6 dredges, and the
remainder was chiefly from hydraulic and sluicing mines.
The
silver production in Idaho was 7,369,742 fine ounces, an increase of
328,109 ounces over the output of 1909. With the resumption of
shipments of lead ore from Gilmore there was a marked increase in
output from Lemhi County, and the Stewart and Caledonia mines assisted
in increasing the production of Shoshone County, which yielded nearly
91 per cent of the production in 1910; but a large decrease was
reported from Owyhee County. Of the total silver production in Idaho,
lead ores supplied 88 per cent, or 6,479,636 ounces; copper ores 6.4
per cent, or 475,363 ounces; and siliceous ores 5.3 per cent, or
393,795 ounces. As usual, the Coeur d'Alene region of Shoshone County,
including the Hunter, Lelande, Yreka, and smaller districts, supplied
the bulk of the State output—6,703,080 ounces in 1910, against
6,201,157 ounces in 1909. Of the county production in 1910, there were
derived from lead ores 6,238,518 ounces and from copper ores 446,471
ounces—an increase from the first source, but a decrease from the
second. Owyhee County produced 341,482 ounces of silver from siliceous
ores in 1910, and Lemhi County 150,185 ounces, mainly from lead ores.
Crude ore shipped to smelters contained 2,588,431 ounces of the Idaho
output in 1910, concentrates contained 4,463,517 ounces, and bullion
from gold and silver mills contained 315,356 ounces.
Michigan.—The
Michigan copper mines produced 330,500 fine ounces of silver in 1910
against an output of 286,430 ounces in 1909. The silver production is
mainly from the electrolytic refining of the copper produced, and, as
refining may proceed at a different rate from mining, increased
production of silver indicates increased refining only. The average
recovery per ton of "rock" was 0.03 ounce in 1910. Of the total output
of the State, 293,387 ounces of silver, or 88.7 per cent, came from
Houghton County, and the remainder, 37,113 ounces, was from Keweenaw
County. Six of the 8 mines producing silver were in Houghton County, in
which the production was mostly from amygdaloid ores.
Missouri, Illinois, and Kentucky.—The
lead and zinc mines of the Central States contribute little silver as a
by-product. The small production is mainly from lead ores of southeast
Missouri, where the silver content is only about 1.2 ounces per ton of
concentrates saved, and lead from only about one-sixth of these ores is
desilverized. The output of silver in Missouri in 1910 was 33,096 fine
ounces from 35,002 short tons of concentrates, against 14,188 ounces
from 31,000 tons in 1909.
In
Illinois the silver production in 1910 was 2,022 fine ounces from 398
tons of lead concentrates, against an output of 1,001 ounces from 403
tons in 1909.
In
western Kentucky 84 fine ounces of silver were recovered in 1910 from
56 tons of lead concentrates obtained from lead-fluorspar mines.
Montana.—The
production of gold in Montana in 1910 was $3,730,486, a decrease of
$61,024 from the output of 1909. The decrease was in output from dry or
siliceous and copper ores, as the gold production from placers, lead,
zinc, and copper-lead ores
