a
Other States that have produced gold by dredges are Colorado, which
yielded, 1901-1920, $6,328,819; Idaho, 1897-1920, $4,287,798; Montana.
1896-1920, $9,365,078; Oregon, 1902-1920f$3,554 900; andNew
Mexico, Nevada, South Dakota, Wyoming, Alabama, Georgia, and North
Carolina, a combined yield, 1902-1920, of $323,886.
Of
the output in 1920 California produced $6,900,366 from 40 dredges,
Alaska $1,129,932 from 22 dredges, Montana $255,550 from 3 dredges,
Colorado $512,876 from 5 dredges, Idaho $101,679 from 3 dredges, and
Oregon $358,884 from 4 dredges. One dredge was operated below Silver
City, in Lyon County, Nev., by the Gold Canyon Dredging Co. during the
later part of 1920, but no dredges were working in Wyoming, South
Dakota, or the Appalachian States.
DRY AND SILICEOUS ORES.
The
siliceous ores are in part free-milling (amalgamating), as in Alaska,
California, Arizona, and Oregon; both amalgamating and concentrating,
as in many States; simply concentrating ores, as in parts of Colorado
and Arizona; all-sliming and cyaniding ores; and finally smelting ores.
Tailings both from old dumps and from present millings are largely
reworked by concentration and subsequent cyanidation. Owing to the
increase in the cost of labor and supplies in the last four or five
years, much of the old tailings could not be reworked at a profit.
The
material smelted consists mainly of concentrates and of siliceous and
pyritic ores, which are also valuable as fluxes. Exact figures of
relative output by methods and by States are given in another table.
