amounted
to 87 per cent of all the ore sold or treated, yielded 90 per cent of
the total output of gold. Slightly more than 2 per cent came from lead
ore, nearly 6 per cent from placers, and the remainder from other
classes of ore. The placer production in 1919 was $550,562, an increase
of $24,360. Summit County produced 84 per cent and Lake County nearly
15 per cent of the placer gold. Dredges in these two counties recovered
more than 98 per cent of the placer gold.
Silver.—The
mine production of silver in Colorado in 1919 was 5,758,010 fine
ounces, a decrease of 1,305,544 ounces. Lake County, principally
Leadville, produced 1,542,324 ounces, a decrease of 747,797 ounces. San
Miguel County produced 1,100,942 ounces, an increase of 264,372 ounces.
Siliceous and dry ores yielded 73.5 per cent of the silver recovered,
lead ores 18.55 per cent, lead-zinc ores 5 per cent, and copper ores
less than 2 per cent. The remainder came from placers, zinc ores, and
copper-lead ores.
IDAHO.
Gold.—The
mine production of gold in Idaho in 1919 was $713,238, an increase of
$10,422. The total production of gold from Idaho from the discovery of
placer gold in 1863 to the end of 1919 is estimated at $132,327,023 by
C. N. Gerry.4
Boise
and Shoshone counties were the largest producers of gold in 1919 and
yielded about 84 per cent of the total output. The lode mines produced
gold valued at $522,486. The placer mines produced $190,752 in gold in
1919, of which $164,854 was won by dredging. The total output of gold
recovered by dredges from 1897 to the end of 1919 has been $4,186,119.
Of the total gold in 1919 about 27 per cent came from placers, 65 per
cent from siliceous ores, 3 per cent from copper ores, and the
remainder from lead and lead-zmc ores.
Silver.—The
mine production of silver in Idaho in 1919 was 5,579,056 fine ounces,
or 3,593,284 ounces less than in 1918. The total yield of silver from
Idaho for the period 1863 to 1919, inclusive, is 239,457,351 fine
ounces.5
There
was a decrease of 43 per cent in the output of silver from Shoshone
County, which yielded 86 per cent of' the total quantity of silver in
1919^ 92 per cent in 1918, 93.4 per cent in 1917, 95 per cent in 1916
and 1915, and 98 per cent in 1914. Lead ores contained 85 per cent of
the output of silver and lead-zinc ores 8.8 per cent. Crude ore
shipped, which averaged 20.14 ounces of silver a ton, supplied nearly
29 per cent of the silver, and concentrates, which averaged 20.18
ounces of silver a ton, contained more than 71 per cent of the total
silver. The decreased quantity of lead and copper ores mined had the
effect of curtailing the production of silver.
MAINE AND VERMONT.
A
small quantity of gold and about 6,356 ounces of silver were obtained
from copper ores and old slag shipped from the Pike Hill, Ely, and
Elizabeth mines in Vermont and the Douglas mine at Blue Hill, in Maine.
4 V. S. Geol. Survey Mineral Resources, 1919, pt. 1, p. 451.
5 Op. cit., p. 451.
