Domestic sources.—Platinum
has been found in small quantities, in various parts of the country,
associated with free gold in placer deposits. Indeed its distribution
has been almost co-extensive with these deposits, but in most
localities the quantity is altogether too small to admit of economic
working, and it is only from the placers of the Pacific slope, north of
the Central Pacific railroad, that it has been produced in
merchantable quantity. The following are the localities at which most
of the platinum heretofore collected in California has been procured:
Hay fork, a branch of the Trinity river, occurring here in fine grains,
mixed with the placer gold, to an extent sometimes sufficient to reduce
the value of the gold by 8 to 10 per cent.; on the North fork of the
Trinity platinum is less plentiful but occurs in larger grains, the
largest pieces ever found weighing between 2 and 3 ounces; in Butte
county, in the hydraulic mines around Cherokee and Oroville,
occasionally for nine parts of gold found in this locality one part is
found of platinum and its allied metals; in Mendocino county, in
Anderson valley, Novarro river; in Plumas county, on the principal
forks of Nelson creek and at Badger and Gopher hills; on the Salmon
river, and in the beds of the larger streams in Sierra, Trinity, and
Del Norte counties; on the ocean beach between capes Blanco and
Mendocino; on the Merced and Tuolumne rivers. Going farther north the
amount of platinum increases. On the Oregon coast the proportion of
gold to platinum in the placers is sometimes 5 to 1, and in rare
instances the amount of platinum equals the gold. Platinum has been
reported as occurring in Idaho, and in the Black canon, and on the Agua
Frio, in Arizona, though the occurrence in the latter Territory is not
well authenticated.
Foreign localities.—The
most important sources of platinum are the hydraulic mines at
Nizhne-Tagihlsk and Goro-Blagodat, in the Ural mountains, where the ore
is found with chrome iron ore in serpentine. About 80 per cent, of the
world's production comes from this source. Next in importance are the
gold washings of the Pinto, in the province of Antioquia and the
headwaters of the Atral river in the United States of Colombia, where
it is bought by the traders in inland towns and sent to Buenaventura,
thence to Paris ; about 15 percent, of the entire product comes from
this source. In Brazil the ore is found in the province of Minas
Geraes, associated with syenite. It is found also in the Natoos
mountains in Borneo, in Hayti, Peru, India, Australia, and in the sands
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