530 MINERAL RESOURCES, 1920—PART I.
WYOMING.
The total production of gold in Wyoming from 1867 to the end of 1920 is given by Charles W. Henderson7 as $1,236,059, and the output of silver for the same period as 69,691 ounces.
No production of gold or silver was reported by mines in Wyoming in 1920.
PHILIPPINE ISLANDS.
The
output of gold in the Philippine Islands from 1907 to 1920, inclusive,
has been $11,635,805. The mine production of gold for 1920 was
$1,276,561, against $1,309,722 in 1919, $1,290,000 in 1918, $1,408,161
in 1917, $1,514,200 in 1916, $1,320,900 in 1915, $1,371,514 in 1914,
$868,362 in 1913, and $570,212 in 1912.
The
milling plant of the Benguet Consolidated Mining Co. in the Province of
Luzon, the largest producer of gold in the Philippine Islands, is
described in the Mining and Scientific Press of December 4 and 11,
1920. In 1920 about 35,600 tons of ore were cyanided and yielded $15.02
a ton in gold and silver. The cost of mining and milling the ore was
given as $8.02 a ton. Another large producer was the Colorado mine at
Aroroy.
The
mine production of silver in the Philippine Islands in 1920 was 22,118
ounces and was recovered entirely from gold bullion refined, as no
attempt was made to develop the known deposits of silver ore.
NUMBER OF PRODUCING MINES.
The
following table indicates the number of mines producing gold and silver
in 1920. The placers are those in which the gold and the silver in
natural alloy with the gold and, in a few placers, found also with
platinum are recovered from gravels and sands, whether by hand washing,
sluicing, hydraulicking, drifting (in frozen ground or ancient buried
river channels), or by dredging. The deep mines are those producing
gold and silver (from ores as distinguished from gravels) mainly from
underground workings, including those whose ores are valuable chiefly
for copper, lead, or zinc but which contribute precious metals as
by-products. In addition to producing mines here enumerated, many
properties were being prospected and developed (though prospecting and
development were much less active than usual) without making any output
in 1920, and many other mining claims were being held by assessment
work only.
The
enumeration of placer mines is less satisfactory than that oi deep
mines, because some of the operations are only temporary and
individually small and because much of the production is made b\
transitory miners not regularly working placer ground. The unit so far
as possible is, however, as for deep mines, not the operator, but the
mining claim or group of claims.
> U. S. Geol. Survey Mineral Kesources, 1920, pt. 1, p. 155.
