Owing to the presence of osmiridium in considerable proportion, the ore is classed as “hard metal,” and on that account fetches a higher price. Many of the richer placers have become exhausted, and work is now carried on by a few individuals, principally Chinese, who work during the summer months only. In some cases high benches, 50 to 100 ft. above the creek bottom, are being worked. Much of the platinum and gold is of a coarse texture, with a rough surface, and the latter is sometimes found embedded in quartz. Nuggets are sometimes found encrusted with chromite, and are thus liable to be overlooked. The deposits are therefore not of great age, and the metals have not been transported long distances from their sources.
Kemp is of opinion that the platinum is derived from pyroxenite dykes cutting through peridotites, which outcrop on Olivine and Grasshopper Mountains.
It is of interest to note that some diamonds and rubies have been discovered with the platinum in the Tulameen deposits. They are of good quality, but of small size, and occur in a matrix of dunite[[28]] p. 210. American capital dominates the platinum industry in the district. In 1918, at the request of the Imperial Munitions Board, special investigations in this area were undertaken by members of the Geological Survey, and several prospecting bores were put down to bedrock. Full reports of the work done are not yet available, but it is understood that the results are considered to be promising, and to warrant further examination of the district[[29]] p. 429.
Platinum was in 1918 discovered at Franklin Camp, near Grand Forks, B.C., in the “Black Lead,” so-called, which is a mixture of augite, 75·13 per cent.; orthoclase and microcline, 17·06 per cent.; hornblende, 1·47 per cent.; and magnetite, 6·06 per cent., as determined by microscopic measurements on a typical specimen, with accessory minerals, chalcopyrite, bornite and apatite. A sample of chalcopyrite assayed 0·38 oz. crude platinum per ton. Samples of the “Black Lead” assayed from 0·02 to 0·17 oz. per ton[[31]].
At Burnt Basin, on the Mother Lode claim, an auriferous quartz vein carries platinum, in amounts varying from a trace to 0·25 oz. per ton. The quartz also contains chalcopyrite, pyrite, galena, sphalerite and molybdenite[[31]]. Native platinum in small quantities has been found associated with gold in the following localities: Tranquille River, Fraser River, Rock Creek, Yale District, North Thompson and Clearwater Rivers. It has also been reported to occur in a dyke across the Kootenay River upon the Granite Poorman Mining Company’s property a few miles from Nelson[[32]]. At Siwash Creek, in the Tulameen district, small flakes of platinum, associated with chromite, often occur in shear zones in granite. Dredging for gold and platinum is being carried on, on the Peace River, North British Columbia.
According to J. B. Hobson the heavy concentrate produced on the Consolidated Caribo hydraulic mine at Quesnel, contains, besides gold and silver, platinum, palladium and osmiridium, one analysis giving a total value of $3,873 per ton. The gold and silver being non-amalgamable are probably included in particles of pyrite and galena, whilst the platinum metals are found as minute grains or are enclosed in particles of chromite and magnetite. A system of “under-currents” is being installed to properly dress this concentrate[[33]].
In 1917 the recorded output of crude platinum from the placer gravels of the Tulameen district in British Columbia was 57 oz., that for 1918 being 39 oz. For the five years preceding 1892, this district produced on an average over 1,500 oz. per year.
Manitoba.—Samples of gold ore containing platinum have been obtained in the Star Lake district of south-eastern Manitoba[[34]]. Analyses of the samples from different auriferous reefs were made by the Department of Mines in 1917, and yielded platinum varying in amount from a trace to 0·1 oz. per ton. In addition to gold and platinum, the veins carry small quantities of galena, zinc blende, pyrite, chalcopyrite and arsenopyrite in a gangue consisting mainly of quartz.
Platinum is reported to occur in auriferous quartz veins in several mines and prospects in Le Pas district; a picked sample of ore from the mine of the Northern Manitoba and Development Company, assayed $49 gold and $17 platinum per ton[[35]]. McCafferty’s Prospect, about 5 miles away, contains platiniferous quartz.
Nova Scotia.—According to E. R. Faribault in Summary Report, 1918, Part F, of the Canadian Department of Mines, platinum has been found, mostly in traces, in some of the old gold districts of Halifax county and, lately, in the tungsten concentrates of the Moose River mines. So far, all occurrences are in quartz veins in the lower quartzite and slate formation of the gold-bearing series of the Atlantic coast. The platiniferous mineral is supposed to be sperrylite, with which is associated arsenopyrite.