2
per cent came from lead ore, 4 per cent from placers, and about 1 per
cent from copper ore, and the remainder from other classes of ore. The
placer production in 1916 was $712,924, an increase of $19,614. Summit
County produced nearly 81 per cent and Lake County 17 per cent of the
placer gold. More than 99 per cent of the placer gold from these two
comities was recovered by dredges.
Silver.—The
mine production of silver in Colorado in 1916 was 7,656,544 fine
ounces, an increase of 628,572 ounces. Lake County, principally
Leadvule, produced 2,931,281 ounces, an increase of 360,279 ounces. San
Miguel County produced 812,041 ounces, a decrease of 284,600. There was
a considerably larger production of silver from Ouray and Pitkin
counties and decreased outputs from Chaffee, Dolores, San Miguel, and
La Plata counties. Sdiceous and dry ores yielded 73 per cent of of the
silver received, lead ores 15 per cent, lead-zinc ores 7 per cent, and
copper ores 3 per cent. The remainder came from placers, zinc ores, and
copper-lead ores.
IDAHO.
Gold.—The
mine production of gold in Idaho in 1916 was $1,115,810, a decrease of
$63,921. The total production of gold from Idaho from the discovery of
placer gold in 1863 to the end of 1916 is estimated at $130,106,160 by
C. N. Gerry.1
Boise
and Elmore counties were the largest producers of gold, yielding about
60 per cent of the total output. The lode mines produced gold valued
at $666,717. The placer mines produced $449,093 in gold in 1916, of
which $327,696, or 73 per cent, was won by dredging. The total output
of gold recovered by dredges from 1897 to the end of 1916 has been
$3,722,056. Of the total gold in 1916 about 40 per cent came from
placers, 47 per cent from siliceous ores, 7 per cent from copper ores,
and the remainder from lead and lead-zinc ores.
Silver.—The
mine production of sdver in Idaho in 1916 was 12,300,873 fine ounces,
or 531,745 ounces more than in 1915. The total yield of silver from
Idaho for the period 1863 to 1916, inclusive, is 212,676,617 fine
ounces.1
There
was an increase of 4 per cent in the silver output from Shoshone
County, which yielded 95 per cent of the total quantity of silver in
1915 and in 1916, against 98 per cent in 1914. Lead ores contained 66.5
per cent of the output of silver and lead-zinc ores 30 per cent. Crude
ore shipped, which averaged 16.22 ounces of silver a ton, supplied
nearly 32 per cent of the silver, and concentrates, which averaged
21.53 ounces of silver a ton, contained more than 67 per cent of the
total silver. Inability to handle and smelt all the ores mined had the
effect of curtading the production of silver.
MAEYLAND, PENNSYLVANIA, NEW HAMPSHIRE, AND VERMONT.
There
was only a small production of silver reported by copper mines in
Frederick County, Md., in 1916, although work was done on prospects in
Montgomery County, Md., and copper-bearing concentrates continued to
be shipped from the Cornwall magnetite mines at Lebanon, Pa.
1 U. S. Geol. Survey Mineral Resources, 1916, pt. 1, p. 565,1917.
