Possibility of new discoveries in California and Oregon.—It seems very unlikely that any important discoveries of platinum sand will be
made in the well-prospected gold-bearing districts. The presence of
platinum along the whole coast of California shows that it has been
transported from the adjacent land area and, as serpentine areas occur
extensively in the coast ranges, it is well possible that within this
mountainous district localities may yet be found which will prove
richer in platinum than the occurrences thus far known.
The
coast ranges have been prospected but little, as the larger part of
them is entirely barren of gold-bearing deposits, and it may be well
worth while to examine these districts by panning the gravels in order
to ascertain whether any of these serpentine and peridotite areas may
not contain more platinum than those occurring in the well-prospected
gold-bearing areas. Although probably all peri-dotites and some
pyroxenites contain a little platinum, yet it is evident that only in
few places in the world does the metal occur in economically important
quantities.
Other States.—The
literature contains frequent mention of platinum in gold-bearing
gravels in the States outside of California and Oregon. It has been
reported from Arizona. In Colorado it is reported from Buena Vista in
Chaffee County, Aspen in Pitkin County, Liberty in Saguache County, and
Tellunde in San Miguel County. In Idaho it is reported from the Payette
River and Snake River sands, also at Rocky Bar, in Elmore County, at
Elk City district in Idaho County, on North Fork of Clearwater River in
Idaho County, and at Pierce City in Shoshone County. In Montana,
according to D. T. Day, it is found in concentrates from Princeton in
Granite County. In northeastern Oregon it occurs at Durkee in Baker
County, and also, it is stated, near Sumpter; it is also mentioned as
occurring in sands at Foster in Lynn County, at La Grande in Union
County, and at Hills-boro in Washington County. In Utah it is reported
at Hite in Garfield County. In Washington it is found on the beaches
in Clallam County, and on Sand Island in Pacific County.
The
occurrence of platinum in copper ores, mostly of pre-Cambrian age, in
Wyoming and Nevada has already been mentioned. In these ores there is
usually more palladium than platinum. Copper and gold bullion generally
contains a small quantity of platinum metals, which is saved in some
refining processes.
In
the Eastern States platinum is rare but has been reported from Lumpkin
County, Ga., from Maryland near Baltimore, and from Rutherford County,
N. C. A nugget of platinum weighing 104
g
rams was once found in the glacial drift near Plattsburg, N. Y. It was intergrown with chromite.
FOREIGN COUNTRIES.
Central America, West Indies, and Mexico.—Platinum
sands are reported from Honduras and from the island of Santo Domingo.
In Mexico platinum is evidently extremely rare, and no reliable data of
its occurrence are available.
Brazil.—Platinum
was observed at an early date in the gold washings of Minas Geraes, but
very little, if any, of the metal has actually been recovered.
Borneo.—Platinum was discovered in 1831 in the gold washings of southeastern Borneo in gravels derived from serpentine, diorite,
