GOLD AND SILVER.
859
valued
at $694,053 came from 196 placers and gold valued at §650,506 from 188
deep mines in 1913. In 1912 the placers produced $632,029 and the deep
mines $749,185. Nearly 81 per cent of the placer gold output in Idaho
in 1913 was produced by dredging. Or the total production 51.6 per cent
was derived from placers, 34.4 per cent from dry or siliceous ores, 7.7
per cent from copper ore, 5.2 per cent from lead ore, and the small
remainder from lead-zinc ore. From the gold-milling ore treated,
$174,927 was recovered by amalgamation and $187,915 by cyanidation.
Concentrates shipped produced $88,304, and crude ore $199,360. Boise
County led hi production with $620,070, of which $529,893 was from
placers, mainly dredge operations in the Boise Basin district, and
$90,177 was from siliceous ores, chiefly in the same district. Lemhi
County followed with $276,306, of which $106,714 was from placers and
$158,627 from siliceous ores. Owyhee and Idaho counties also produced
notably from these ores, and Custer County from copper ores.
Silver.—The
recoverable output of silver from Idaho in 1913 was 9,989,139 fine
ounces, the record production, against 8,294,745 ounces in 1912. This
represents the notable increase of 1,694,448 ounces, more than 20 per
cent in quantity, and of $932,205 in value, over the high production of
1912. The largest part of the increase was from lead-zinc and lead
ores. Of the total output in 1913 lead
ores
produced 78 per cent, lead-zinc ores 16 per cent, and copper ores about
4 per cent. Concentrates produced from milling and
separating
lead and lead-zinc ores yielded 6,720,969 ounces, and crude shipping
ore 3,158,355 ounces. The bulk of the State yield was from the great
Coeur d'Alene silver-lead-zinc mines in Shoshone County, whose lead
ores supplied 7,461,406 ounces and whose lead-zinc ores produced
1,577,117 ounces in 1913.
MARYLAND AND PENNSYLVANIA.
Silver.—There
was no production of silver reported in 1913 from the copper ores of
either Maryland or Pennsylvania. In the past there has been some small
silver output from refining the copper recovered, principally from the
New London mines of Maryland and the Cornwall iron mine of Lebanon,
Pa., from the ores of which last-named mine copper sulphides have been
separated and shipped.
MICHIGAN.
Silver.—The
Michigan copper mines produced 295,173 fine ounces of silver in 1913,
against 528,453 ounces in 1912, the decreased output being a reflection
of the labor troubles of 1913, which caused a falling off in copper
mining. The silver production is mainly from the electrolytic refining
of the copper produced. The average recovery of silver per ton of
"rock" treated in 1913 (both conglomerate and amygdaloid) was 0.04
ounce, against 0.05 ounce in 1912 and 0.04 ounce in 1911. Of the total
production in 1913 Houghton County produced 253,030 ounces and Keweenaw
County 42,143 ounces.
MISSOURI, ILLINOIS, AND KENTUCKY.
Silver.—The
lead and zinc mines of the Central States contribute no gold and but
little silver. This last is a by-product, mainly from the refining of
lead from concentrates produced at the lead mines of
