—A small quantity of platinum is produced each year by the placer operations on the Tulameen River, in British Columbia. The metal was derived from a mass of peridotite and dunite, which outcrops west of the main drainage. The gravels of this area are apparently very deep, but the platinum is found in the upper 8 to 20 feet, in part concentrated on a false bed-rock. Recent information indicates the possibility of dredging a considerable acreage of gravels on the Tulameen in the vicinity of Princeton. Reports were current during 1917 of discoveries of platiniferous placers further north in the Canadian Rockies, but no definite information concerning the size or value of the deposits is available.
By far the greater part of the yearly output of platinum and palladium of Canadian origin is a by-product of refining the nickel ores of the Sudbury district, Ontario. That a far greater production of both metals from this source is possible has been shown by the Royal Ontario Nickel Commission.
United States.
—Crude platinum is won in California, Oregon, and Washington. The dredges at the base of the Sierra Nevada Mountains in California produce a large part of the placer platinum output of the United States, principally because of the great yardage handled rather than because of any particular concentration of platinum in the gravels derived from the Mother Lode belt. In northern California the Klamath and Trinity rivers, particularly the Hay Fork of the Trinity, carry platiniferous gravels. In southwestern Oregon platiniferous gravels have been found at several places on the Illinois and Rogue rivers. Along the beach from Bandon, Oregon, to Eureka, California, platinum occurs with the black sands and has been won at a number of mines located both on the present strand line and on ancient elevated beaches. In the Blue Mountains of eastern Oregon and in the Strawberry Range south of John Day River a few placers have been worked which carried platinum. In Washington, particularly on the south fork of Lewis River, near Yacolt, platinum has been found, and it is reported on the beaches from the Straits of Juan de Fuca south.
All of the platinum-bearing placers in the United States are closely associated with chromiferous serpentine derived from peridotites or pyroxenites. The concentration of the platinum has not been great and the original quantity was not large, so none of the areas seems capable of much production. Most of the crude platinum from the Pacific Coast placers carries considerable osmiridium. As stated before, the great bulk of the platinum won in the United States is from the dredging fields at the base of the Sierra Nevada Mountains from Butte to Stanislaus County. The gravels in these fields are the result of several reconcentrations, but their platinum content can not be considered high. In practically all of the other stream placer areas the gravels have not been subject to such extensive reconcentration, and in some places recent gravels carry platinum. The beach deposits are the result of repeated concentration. The platinum and gold are excessively small, flaky, and difficult to separate from the heavy sands; they are concentrated in the dark bands of sand caused by tidal and wave concentration. The lenses are rarely over one foot thick and taper out in short distances. Correct estimates of reserves are consequently almost impossible.
Within the past few years a little platinum has been won from widely scattered localities in Alaska, chiefly Dime, Bear, and Sweepstake Creek placers in eastern Seward Peninsula; the Boob Creek placers, Tolstoi district, Lower Yukon; and the beach deposits of Kodiak Island. Platinum also occurs in the Upper Kahiltna drainage, north of Anchorage.
Copper ores rich in palladium are produced at the Rambler mine, Wyoming, from the Salt Chuck Mine, Alaska, and from the Boss mine, in Nevada. At the two former mines the ore is associated with basic igneous rocks; in the latter mine the ore bodies are in dolomite. The oft-repeated reports of platinum in certain sandstones exposed near the Bright Angel trail in the Grand Canyon of the Colorado, Arizona, and in certain shale beds in Chester County, Pennsylvania, have not been verified, though in June, 1918, the United States Platinum Co. was organized to work the deposits in Arizona.
Australia.
—Platinum and osmiridium have been won in small quantities from Queensland, New South Wales, and Tasmania. Platinum is also reported from New Zealand. The greater production has been from the osmiridium-bearing gravels of the Savage River drainage in the Bald Hills mining district in the northwestern part of Tasmania. Little has been published concerning the extent of these gravels, which were derived from the weathering of a series of sediments intruded by basic igneous rocks.
In New South Wales, beach deposits much like those of California and Oregon are found from Beachy Head north past Clarence and Richmond rivers into Queensland. Commercial exploitation of these deposits seems to have had the ups and many downs of similar undertakings on our West Coast. Some platinum was obtained from an old buried channel in the Platina or Fifield district in central New South Wales, where pay gravel 6 to 10 feet thick lies under an overburden of 20 to 80 feet. The water supply was not in sufficient quantities to warrant large-scale operations. The channel seems small and has been mined about as far as is commercially possible.