ounces
in Alaska, 46,346 ounces in Colorado, and 37,376 ounces in Nevada.
South Dakota showed the only increase, which was a nominal one, in gold
recovered by amalgamation.
The
total yield of silver by amalgamation in 1916 was only 348,177 fine
ounces, valued at $229,097, against 382,459 ounces, valued at $193,907,
in 1915. The output came mainly from California, Oregon, South Dakota,
Alaska, Nevada, and Colorado, in the order given, and consisted chiefly
of silver alloyed with gold.
The
total output of gold by cyanidation in 1916 was 1,260,172 fine ounces,
valued at $26,050,067, against 1,444,077 ounces, valued at $29,851,721,
in 1915. The output was 530,466 ounces in Colorado, 293,625 ounces in
Nevada, 131,020 ounces in South Dakota, 80,337 ounces in Alaska, 63,444
ounces in Arizona, and 56,947 ounces in California in 1916.
The
total silver yield by cyanidation in 1916 was 14,432,378 fine ounces,
valued at $9,496,505, against 16,184,924 ounces, valued at $8,205,756,
in 1915. Nevada led, with the bulk of the output— 11,301,861 ounces—and
was followed by New Mexico with 839,470 ounces, Arizona with 648,382
ounces, Texas with 626,246 ounces, and Colorado with 510,991 ounces.
The most notable losses were in Arizona, 91,399 ounces; New Mexico,
287,276 ounces; Colorado, 59,657 ounces; Montana, 71,290 ounces; and
Nevada, 1,156,900 ounces.
Of
the gold-producing States, whose chief output is from milling ores,
Alaska, California, and South Dakota still yield more gold by
amalgamation than by cyanidation, whereas the latter process produces
more gold than amalgamation in Colorado, Arizona, and Nevada, and it
produces much more silver in Arizona, Colorado, Montana, Nevada, New
Mexico, South Dakota, and Texas. Oregon and California were the only
States in which the recovery of silver by amalgamation exceeded that
by cyanidation. Altogether amalgamation produced gold and silver valued
at $20,168,921 from milling ores in 1916, against $35,546,572 produced
by cyanidation from such ores in that year.
Of
the total output of gold from all sources in 1916, amalgamation
produced 19.8 per cent in Alaska, 39.6 per cent in California, and 63.4
per cent in South Dakota, and cyanidation produced 32.9 per cent in
Arizona, 57.2 per cent in Colorado, 68.4 per cent in Nevada, 25.1 per
cent in New Mexico, and 36.3 per cent in South Dakota.
Of
the total output of silver from all sources in 1916, amalgamation
produced 32.5 per cent in South Dakota and 32.2 per cent in Oregon, and
cyanidation produced 81.7 per cent in Nevada, 47.5 per cent in New
Mexico, 66.4 per cent in South Dakota, and 94.3 per cent in Texas.
For
details of the consumption of quicksilver in the amalgamation milling
process and of potassium cyanide and sodium cyanide in the cyanidation
process the reader is referred to the mines reports of the several
Western States indicated in the prefatory note. Data as to consumption
of these supplies are not yet furnished by a sufficient number of
mining and milling companies to justify tabulation for the entire
United States. It has been estimated by H. D. McCaskey that the annual
consumption of quicksilver in the amalgamation process in the United
States (including Alaska) for the period 1911 to 1916, inclusive, has
varied between 80,000 and 100,000 pounds.
