mining
was of much importance in the past and had become a special branch of
the industry in itself, but restrictive laws relative to the debris and
to disturbance of navigable streams have in recent years greatly
confined mining activity of this kind. Finally, there is a small annual
output of gold from dry placers in the- Southwest and also a production
of gold and platinum from ocean-beach mining in California and Oregon.
Some
interesting notes on beach mining in California and Oregon and on dry
placets in California, by Charles G. Yale, and on dry placers in
Arizona, Nevada, and New Mexico, by V. C. Heikes, were published in
the Survey report on gold and silver for 1912, copies of which can
still be had on application to the Director, United States Geological
Survey, Washington, D. C.
A
geologic investigation of the placer deposits of the United States is
now being made by James M. Hill, of the United States Geological
Survey, and cooperative work on the technology is being done by Charles
Janin, of the United States Bureau of Mines. The investigation will
require considerable field study as well as office work, and it is
hoped that operators will assist in furnishing the necessary data
requested, as well as the annual statistics for the Mineral Resources
reports, in order that publication of the results may not be unduly
delayed.
DREDGING.
The
production of gold by dredging in the United States and Alaska from the
commercial beginning of the industry in 1896 to the record output of
1915, inclusive, has amounted according to best available data, to
$107,316,593, of which $79,111,231 came from California, $12,430,894
from Alaska, $7,457,161 from Montana, $3,408,384 from Colorado, and
$3,394,360 from Idaho.
Brief
details of dredging operations have been given in Mineral Resources in
the mines reports on gold, silver, copper, lead, and zinc of the
Western States and also in earlier reports of the Director of the Mint.
A brief history of gold dredging in the United States was given in the
gold and silver (general) report for the year 1914, and the gold
production obtained by dredging in the United States and Alaska from
1896 to the end of 1914 and the number of dredges operated was given by
States for each year. Further information is to be found in reports of
geological surveys or mining officials of different States. A
comprehensive and very useful report is contained in Bulletin 57 of the
California State Mining Bureau, "Gold dredging in California," by W. B.
Winston and Charles Janin. Another valuable treatise is "Dredging for
gold in California," by D'Arcy Weatherbe, published by the Mining and
Scientific Press; and additional information is constantly furnished by
the technical press.
The
gold recovered in the United States and Alaska by 114 gokl dredges in
1915 was $12,483,125, against $12,512,783 by 120 dredges in 1914. Of
the 1915 production California yielded $7,796,465 from 58 dredges,
Alaska $2,330,000 from 35 dredges, Montana $861,626 from 5 dredges,
Colorado $672,386 from 5 dredges, and Idaho $486,541 from 7 dredges.
Two dredges operating in Baker County, Oreg., also had a large output.
