MICHIGAN.
Silver.—The
copper mines of Michigan produced 441,430 fine ounces of silver in
1919, against 509,467 fine ounces in 1918. The silver was derived
mainly from the electrolytic treatment of 29,583,000 pounds of copper.
The average recovery of silver per ton of "rock" treated was 0.27
ounce. Of the total output of silver 393,642 ounces came from mines in
Houghton County.
MISSOURI, OKLAHOMA, ILLINOIS, AND KENTUCKY.
Silver.—The
lead and zinc mines of the Central States produce no gold and only a
comparatively small quantity of silver. Nearly all the silver is a
by-product from the refining of lead from concentrates of lead ores
mined in southeastern Missouri. The total yield of silver from Missouri
in 1919 was 90,401 fine ounces, which, with the exception of 29,480
ounces recovered from cobalt-nickel-copper ore and copper concentrates,
was derived from lead recovered from 81,000 tons of galena
concentrates. The average recovery was slightly more than 0.75 ounce of
silver per ton of concentrate smelted.
The
lead-zinc fluorspar deposits of the Kentucky-Illinois field carry
silver, and from the lead concentrates shipped from Illinois in 1919 a
recovery of 4,440 ounces of silver was recorded, against 8,171 ounces
in 1918. The average silver content per ton recovered from lead
concentrates from Illinois in 1919 was 6.16 ounces. No silver ore was
shipped from the Criswell mine, near Byars, McClain County, Okla., in
1919.
MONTANA.
Gold.—The
mine production of gold in Montana decreased from S3,104,764 in 1918 to
$2,229,588 in 1919. The placer yield was $291,430—a decrease of
$104,802. Silver Bow County had the largest total output—$579,638. Most
of the placer gold was recovered by one company, which operated three
dredges in Alder Gulch, in Madison County. Lewis and Clark County
produced $498,703, and Deer Lodge County $289,980, chiefly from
siliceous ores. At amalgamation and cyanidation plants $730,683 in
gold was produced, or an average recovery of $6.59 per ton of ore and
tailings treated. Ore treated at concentration mills yielded
concentrates containing $525,960, or 46 cents a ton, and crude ore
shipped to smelters contained $654,317 in gold, or an average of $2.19
a ton.
Silver.—Montana
mines produced 12,541,181 fine ounces of silver in 1919, a production
25 per cent less than in 1918. The copper ores yielded 6,341,825 ounces
(an average of 2.06 ounces per ton), of which Silver Bow County (Butte)
supplied 6,327,108 ounces. The lead-zinc ores produced 3,678,353
ounces, of which Silver Bow County supplied 3,506,048 ounces. The dry
or siliceous ores produced 1,707,053 ounces, of which Granite County
supplied 576,183 ounces and Silver Bow County 691,863 ounces.
NEVADA.
Gold.—The mine production of gold in Nevada in 1919 was
$4,541,502, against $6,619,937 in 1918. The production in 1919
from mines in Esmeralda County was $787,579—a decrease of nearly
