NORTH AMERICA
Mexico
Platinum has been shown to exist in the states of Guerrero and Hidalgo in deposits of ferrous clays, which are of undoubted sedimentary origin, and are apparently laterites. The metal exists in a very finely disseminated state, invisible to the naked eye[[64]].
United States
At the beginning of the war there was a considerable shortage of platinum in the country, caused partly by the falling-off of the imports, and in part owing to the increased demand in connexion with munition manufacture.
California is the principal producer of crude platinum, and in 1917 this State supplied 460 oz. out of the total output of 605 oz.; with the exception of a few ounces from the State of Washington, Alaska and Oregon provided the balance.
A considerable quantity of foreign crude and manufactured platinum is imported annually, as shown in the following tables:
| Imports of Manufactured Platinum into the United States | ||||||||
|---|---|---|---|---|---|---|---|---|
| (In troy oz.) | ||||||||
| 1912. | 1913. | 1914. | 1915. | 1916. | 1917. | 1918. | ||
| From British countries: | ||||||||
| Canada | 777 | 582 | 55 | 139 | 511 | 332 | 253 | |
| United Kingdom | 19,169 | 16,595 | 6,476 | 7,692 | 9,513 | 3,195 | 357 | |
| Other British countries | 4 | 5 | 25 | |||||
| Total, British countries | 19,950 | 17,177 | 6,531 | 7,831 | 9,569 | 3,527 | 635 | |
| From foreign countries: | ||||||||
| France | 25,723 | 24,519 | 16,570 | 3,480 | 3,395 | 2,507 | 814 | |
| Germany | 22,673 | 29,075 | 30,015 | 2,350 | 10 | |||
| Netherlands | 159 | |||||||
| Norway | 258 | 120 | ||||||
| Russia (European) | 815 | |||||||
| Colombia | 480 | 207 | 1,665 | |||||
| Other foreign countries | 63 | 512 | 57 | 3 | ||||
| Total, foreign countries | 48,396 | 53,594 | 47,658 | 6,373 | 4,076 | 2,891 | 2,482 | |
| Grand total, oz. | 68,346 | 70,771 | 54,189 | 14,204 | 13,645 | 6,418 | 3,117 | |
| Imports of Crude Platinum into United States | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| (In troy oz.) | |||||||||
| 1911[[N]]. | 1912. | 1913. | 1914. | 1915. | 1916. | 1917. | 1918. | ||
| From British countries: | |||||||||
| Canada | 554 | 45 | 314 | 535 | 139 | 91 | 25 | 76 | |
| United Kingdom | 28,153 | 19,951 | 8,368 | 7,084 | 6,805 | 36,703 | 1,561 | 1,073 | |
| Other British possessions | 7 | 5 | |||||||
| Total, British countries | 28,707 | 20,003 | 8,682 | 7,619 | 6,949 | 36,794 | 1,586 | 1,149 | |
| From foreign countries: | |||||||||
| France | 44,964 | 10,178 | 7,284 | 4,921 | 3,507 | 13,014 | 52 | 166 | |
| Germany | 37,041 | 15,335 | 23,345 | 15,105 | 2,366 | ||||
| Norway | 200 | 442 | 285 | 302 | |||||
| Panama | 160 | 105 | 92 | 12 | 372 | ||||
| Brazil | 118 | 103 | 27 | ||||||
| Chile | 9 | 766 | 3 | ||||||
| Colombia | 5,503 | 6,627 | 10,461 | 12,387 | 13,121 | 25,588 | 21,071 | 25,365 | |
| Other foreign countries | 17 | 13 | 1 | 103 | 99 | 21,663 | |||
| Total, foreign countries | 87,525 | 32,162 | 41,290 | 33,015 | 19,385 | 39,217 | 22,103 | 47,596 | |
| Grand total, oz. | 116,232 | 52,165 | 49,972 | 40,634 | 26,334 | 76,011 | 23,689 | 48,745 | |
[N]. Including manufactured platinum.
In 1917, 38,831 oz. of refined platinum metals, of which 7,384 oz. is believed to have been of domestic origin, were recovered from alloy with other metals, and 72,186 oz. were obtained from the refining of scrap metal, and sweepings. The shortage was also to some extent relieved by the receipt from Russia early in 1918 of a special consignment of 20,922 oz. of crude platinum, which had been collected in 1917 by the Russian-English Bank, and which was taken out of Russia by F. W. Draper and delivered to the United States Government. It yielded 17,640 oz. platinum, 64·75 oz. palladium, 182·11 oz. iridium and 48·56 oz. of rhodium, a total of 85·725 per cent. of platinum metals, slightly above the usual 83 per cent.[[65]].
Alaska.—The first production of platinum in Alaska was in 1916, in which year about 12 oz. were shipped to the United States. In 1917 the output rose to 81 oz., of which 66 oz. were obtained from the Seward Peninsula and 15 oz. from the Copper River country.
In 1918 an increased output of 135 oz. was partly obtained from alluvial deposits and partly as a by-product in the treatment of copper ore of the Salt Chuck mine, Ketchikan[[66]].
This mine is a palladium-copper mine containing mainly bornite with a little chalcopyrite, and the alteration products covellite and chalcocite, the metals present being, besides copper and palladium, gold, silver and platinum. The ratio of palladium to platinum averages 50 to 1. The concentrates produced, representing about 3½ per cent. of the weight of the ore, contain: copper, 40 per cent.; gold, 1·2 oz.; silver, 5·3 oz.; and platinum metals, 3·15 oz. per ton[[67]].
In the Seward Peninsula the larger portion is derived from placer deposits in Dyme Creek, Koyuk district, where the gravels are primarily worked for gold, 1 oz. platinum being obtained for every $5,000 worth of gold. In 1918, 56 oz. were recovered. Bear Creek and Sweepstake Creek have also supplied small quantities of platinum, and a little is derived from placers on Boob Creek, in the Tolstoi district [[50]] p. 19.
A possible source of platinum appears to lie in the neighbourhood of the Red Mountain, on the Kenai Peninsula. The mountain is composed of fine-grained dunite, in which abundant chromite occurs. Up to 1917 no placer mining had been attempted in this locality[[68]].
In the Goodro Mine, at the head of Kasaan Bay, Prince of Wales Island, were found in 1918 both platinum and palladium, the latter in greater amount, and carried in bornite and chalcopyrite; some chalcocite and covellite are present also in the ore. The copper minerals are disseminated through pyroxenite, and the country rock consists of limestones, slates and other sedimentaries. The platinum content is small, but regular, whilst the amount of palladium present is proportional to the amount of copper, there being about 1 oz. of palladium to every 8 to 12 per cent. (units) of copper[[69]].
A Bill has been introduced into Congress providing for the incorporation of the United States Platinum Corporation, with capital stock of $30,000,000, the object of which is to secure a concession from the Government of land areas in Alaska containing platinum sands, and to pay for such privilege, as a royalty or subsidy, one-eighth of the net profits obtained from the working of the concession[[70]].
California and Oregon.—Platinum has been proved to exist over a wide area in placer deposits associated with gold, but the proportion of the platinum metals to the gold is usually small. Platinum is obtained from sands in streams rising in the belt of serpentine rocks in central California, and from the serpentine areas in the Siskiyou and Trinity counties in the north-west of the State, which continue north-east into Curry, Josephine and Jackson counties in south-western Oregon[[52]] p. 300. The sources of the platinum obtained along the foot-hills of the Sierra Nevada were old stream channels on the western slopes of the mountains, which are now buried beneath lava several hundred feet deep. These “deep leads” are also mined by drifting for their gold and platinum contents, and in a few cases a fair amount of the metals is extracted from them. Some platinum is obtained by hydraulic mining, but this is carried on with difficulty, owing to the prevailing scarcity of water[[50]] p. 18.
Platinum occurs in black sands found on the Pacific coast in the counties of Coos, Curry and Josephine, Oregon and Del Norte, California. Formerly these beach deposits were rich in platinum, but at the present small quantities only are obtainable after stormy weather. This area has recently been examined by the United States Bureau of Mines, but the results were disappointing.
In California most of the output of platinum is produced by dredging for gold in the Butte, Calaveras and Stanislaus counties[[50]] p. 19. In Trinity county mining is in progress on the Trinity River, about 4 miles below Junction City, by the Valdos Dredging Co. The output from this source for sixteen months in 1916–17 was stated to be 1,950 gm. Platinum, with gold and osmiridium, is also obtained on the Yuba River, about 12 miles east of Marysville in Yuba county, by the Yuba Consolidated Goldfields[[10]] p. 540. Some alluvial platinum has been recovered at the Bean Hill Gold Mine, situated 12 miles south-east of Placerville, and this locality is at present under investigation[[71]]. Californian metal contains from 25 to 45 per cent. iridium. Its origin is believed to be the serpentine- and olivine-bearing rocks of the Sierra Nevada and other ranges.
In Oregon, in addition to the platinum obtained from the beach deposits near Bullards and Marshfield[[50]] p. 20, it occurs in placer deposits, rich in chromite, in south-west Oregon, the principal output being derived from the Waldo district.
Platinum also exists in small quantities in streams in the neighbourhood of the Blue Mountains, eastern Oregon, where the Powder River Gold Dredging Co., in Sumpter district, produces on a small scale. Other platiniferous localities in eastern Oregon are the Granite and Canyon districts, and Spanish Gulch in Wheeler county[[10]] p. 541.
Colorado.—Platinum is known to exist in the black sands from Clear Creek. Its presence has also been reported in the gold gravels of the Iron Hill placer at Como, where it occurs mechanically combined with magnetite. Another occurrence recently discovered is in a vein worked by the Rollcall Mining Co., near Villa Grove. An assay of material from this vein, taken at a depth of 1,500 ft., showed the following values: gold, 3·2 oz.; platinum, 5·09 oz.; silver, 3·05 oz.; and copper, 3·5 per cent.[[9]] p. 592.
Nevada.—In 1909 the occurrence of platinum in Clark county was noticed by the United States Geological Survey to be in association with copper, nickel and cobalt ores from the Key West and Great Eastern Mines, near Bunkerville. The ore bodies are contained in pegmatites and basic intrusions, which carry pyrrhotite and chalcopyrite, the platinum content in the ore averaging about 0·2 oz. per ton[[72]].
In 1914 platinum, with palladium, was discovered at the Boss Gold Mine, situated 10 miles west of Goodsprings, in Clark county. The mine was originally worked for copper, and later for its copper and gold contents. The country rock consists of limestone of middle Carboniferous age, intruded by sills of quartz monzonite porphyry, the ore bodies occurring in a fault zone in the limestone. The copper ores comprise mainly chrysocolla and malachite, and contain traces only of platinum. The gold ore occurs in a fine-grained siliceous matrix, containing a bismuth-bearing variety of plumbo-jarosite (a hydrous sulphate of iron and lead). The rare metals are present in the free state, being apparently alloys of gold, platinum and palladium[[73]].
In 1919 the Boss Mine shipped $22,365 worth of platinum-bearing ore[[74]]. A plant of 300 tons monthly capacity has recently been erected at Los Angeles, California, for the treatment of its complex ores, which average 7 per cent. of copper, 4 per cent. bismuth, and 1·0 oz. of platinum and palladium, 0·75 oz. of gold, and 3 oz. of silver per ton. The pulp from ore pulverized to 80 mesh is agitated with sulphuric acid (2 per cent.). The acid solution contains the copper and about 20 per cent. of the platinum. The copper is precipitated as cement copper, together with the platinum, by means of scrap-iron. The remainder of the platinum, together with the gold and silver, is first leached with, and then precipitated from, a neutral solution of calcium chloride. The inventors of the process claim that approximately 92 per cent. of the copper, 96 per cent. of the platinum metals, gold and silver, and over 90 per cent. of the bismuth are recovered by this process[[75]].
Metals of the platinum group have recently been shown to exist in small quantities in the ore of the Oro Amigo Mine, situated between 1 and 2 miles north-east of the Boss Mine. This ore differs from that of the Boss Mine, in that bismuth and plumbo-jarosite are absent. According to H. K. Riddell, the platinum metals content averages from a trace to 0·1 oz. per ton of ore.
North Carolina.—At Mason Mountain, in Mason county, platinum occurs associated with rhodonite, garnet, biotite and iron sulphides in metamorphic deposits.
New York.—It was reported a few years ago that platinum existed in large quantities in alluvial sands of the Adirondack region. J. M. Clarke, the New York State Geologist, examined the occurrence in 1917, and found that platinum was present in traces only, the deposits being of no economic importance [[10]] p. 541.
Pennsylvania.—At Lancaster county platinum is associated with pyrite, chalcopyrite and galena in mica-schist, and also at Boyertown in black Triassic shale.
Washington.—The production of platinum on a small scale has been reported from beach deposits at the mouth of the south fork of the Lewis River near Yacolt, and also on beaches southward from the Straits of Juan de Fuca[[10]] p. 542. The metal has also been located at various places in the Cascade Mountains in the central part of the State.
Wyoming.—Palladium and platinum, in the proportion of 3 to 1, are obtained at the Rambler Mine, in Albany county, the metals occurring as sperrylite in copper ore, contained in the kaolinized portion of a dunite dyke, intrusive into granite gneiss. The ore consists of covellite, chalcocite, chalcopyrite and tetrahedrite, with nickel and gold[[76]]. It is stated that the platinum and palladium contents vary directly with the percentage of copper present, a typical assay giving the following values: copper, 5 per cent.; gold, 0·02 oz.; silver, 1 oz.; palladium, 0·4 oz.; and platinum, 0·6 oz. per ton[[77]].
Utah.—Platinum and gold in very fine particles occur in the Green River, east of Vernal; also in the Colorado River, near Hite, below the mouth of the Green River. Attempts to mine these deposits have so far proved unsuccessful, due largely to the inaccessibility of the region, as well as the finely-divided condition of the platinum[[42]] p. 11.