CHAPTER III
SOURCES OF SUPPLY OF PLATINUM METALS
(_b_) FOREIGN COUNTRIES
EUROPE
FRANCE
Platinum metals are not produced in France, but platinum is known to occur at several places. In the Department of Charaste and Deux Sevres it occurs associated with pyrite and limonite; in the Valle du Drae, Hautes Alpes, above Chatalard, platinum occurs in tetrahedrite in metamorphic limestone; at St. Arey, near La Mure (Isere), it occurs in bournonite, in dolomite and altered limestone. Platinum is found in argentiferous tetrahedrite and malachite near Presles, in Savoy[31].
As mentioned below, under Russia (p. 36), France controlled the production of platinum in Russia before the war through the Compagnie Internationale du Platine, due to its extensive ownership of platinum deposits and its contracts with Russian companies.
The accompanying table gives a summary of recent imports, with countries of origin, as far as can be obtained.
_Imports_
Recent imports in kilograms (42·87 troy oz.) into France of crude, manufactured and scrap platinum, were as under:
─────╥────────┬───────┬────────┬───────┬──────────── From ║ United │Russia.│Germany.│Serbia.│Switzerland. Year.║Kingdom.│ │ │ │ ─────╫────────┼───────┼────────┼───────┼──────────── 1910 ║ 480│ 5,878│ 1,104│ 204│ 85 1911 ║ 575│ 6,895│ 822│ 782│ 127 1912 ║ │ 5,454│ 283│ 144│ 1913 ║ 78│ 4,500│ 220│ │ 2 1914 ║ 63│ 2,595│ 161│ │ ─────╫────────┼───────┼────────┼───────┼──────────── 1915 ║ │ │ No│details│available 1916 ║ │ │ │ │ 1917 ║ │ │ │ │ 1918 ║ │ │ │ │ ─────╨────────┴───────┴────────┴───────┴────────────
─────╥────────────────┬──────────╥────── From ║Austria-Hungary.│ Other ║Total. Year.║ │countries.║ ─────╫────────────────┼──────────╫────── 1910 ║ │ 44║ 7,795 1911 ║ │ 192║ 9,393 1912 ║ 271│ 84║ 6,235 1913 ║ 171│ 97║ 5,067 1914 ║ │ 102║ 2,921 ─────╫────────────────┼──────────╫────── 1915 ║ No details│available ║ 188 1916 ║ │ ║ 578 1917 ║ │ ║ 578 1918 ║ │ ║ 41 ─────╨────────────────┴──────────╨──────
GERMANY
Platinum has recently been discovered in Westphalia, deposits having been found in Freudenberg, Siegen, Meschede, in Siegerland, Sauerland and Westerwald. It occurs in a series of fragmental deposits, including principally slates and graywackes, the latter composed of quartz and slate, with an argillaceous cement; it is also occasionally found in the recemented fragments which are presumably derived from the basal granite formation, underlying the platinum series[46] p. 606. The beds are believed to be of marine origin, and are probably of Silurian and Devonian age. The platinum, which is present in a very finely-disseminated state, is associated with chromium, nickel, arsenic, antimony, iron, copper, lead, zinc, silver and gold, some of which appear to have been introduced by solutions at a stage subsequent to sedimentation. Krusch investigated these deposits in 1914, and is of opinion, in view of the similarity of the chemical associations with those of the Ural and British Columbian formations, that the original source of the platinum was peridotite, or other form of basic igneous rock. A number of samples, analysed by Krusch, yielded values ranging from a trace to 33·5 gm. (1 oz. troy) platinum per ton[47]. At the outbreak of war the capital necessary for exploitation had not been raised, but in 1918 it was stated that treatment works had been erected at Wenden[2].
As mentioned above, about 25 per cent. of the Russian output of platinum before the war was refined in Germany, and it is known that German capital was helping to finance the pre-war platinum operations of that country[2].
_Imports_
The following is a summary of imports into Germany of crude, manufactured and scrap platinum in kilograms (42·87 troy oz.) for the years 1910–13:
─────┬────────┬───────┬────────────────┬───────┬───────┬──────────┬─────── From │ United │France.│Austria-Hungary.│Russia.│United │ Other │Total. Year.│Kingdom.│ │ │ │States.│countries.│ ─────┼────────┼───────┼────────────────┼───────┼───────┼──────────┼─────── 1910 │ 419│ 846│ 265│ 278│ 127│ 216│ 2,151 1911 │ 292│ 895│ 451│ 190│ 255│ 239│ 2,322 1912 │ 458│ 642│ 554│ 272│ 48│ 307│ 2,281 1913 │ 191│ 683│ 233│ 451│ 236│ 230│ 2,024 ─────┴────────┴───────┴────────────────┴───────┴───────┴──────────┴───────
RUSSIA
Up to the year 1914, Russia produced about 93 per cent. of the total world’s supply of platinum, the metal being derived from extensive deposits of alluvial sands in the Ural Mountains. The platiniferous area extends approximately 80 miles along the central part of the chain of mountains in the Government of Perm, and along the eastern slope, the principal centre of the placers being at Goroblagodat, and on the western side at Nizhni-Tagilsk.
Platinum was first discovered in the Urals in 1823, and exploitation commenced in the following year. In 1828 the Russian Government instituted platinum coinage, which consisted of 3–rouble, 6–rouble and 12–rouble pieces, the coins containing about 2 per cent. iridium. A 3–rouble piece weighed 10·31 gm., and the price paid by the Government to the producers was 16_s._ 10_d._ per oz.; but owing to the subsequent rise in value of platinum, the coinage was discontinued in 1845[48] p. 606.
The platinum industry began to develop in 1869, the price at that time being under £5 per lb.[49], but from that year onwards the value, although subject to considerable fluctuations, has steadily increased. It has been estimated that since the beginning of the industry in Russia, about 6,000,000 oz. of platinum have been recovered from 30,000,000 to 40,000,000 c. yd. of gravel.
As was explained in Chapter I, the official statistics of the Russian output of crude platinum are considered to be low. In the following table, the estimated and official figures of production are given for the years 1910–17:
_In oz. troy_ Year. Estimated output. Official output. 1910 300,000 176,334 1911 280,000 187,008 1912 300,000 177,596 1913 275,000 157,735 1914 240,000 157,182 1915 124,000 119,789 1916 90,000 78,682 1917 50,000
In the official statistics the Ural mining district is divided into five principal areas. The following table shows the annual outputs by districts in recent years:
_In oz. troy_ ────────────────┬───────┬───────┬───────┬───────┬───────┬───────┬────── District. │ 1910. │ 1911. │ 1912. │ 1913. │ 1914. │ 1915. │1916. ────────────────┼───────┼───────┼───────┼───────┼───────┼───────┼────── South Verkhotur │111,070│121,314│118,048│102,552│106,528│ 80,985│52,353 Perm │ 46,068│ 46,885│ 38,709│ 36,878│ 38,050│ 22,996│14,818 North Verkhotur │ 11,862│ 11,362│ 13,166│ 11,376│ 7,426│ 12,288│ 9,968 Tcherdynsk │ 6,359│ 5,016│ 6,162│ 6,109│ 4,753│ 3,518│ 1,542 South │ │ │ │ │ │ │ Ekaterinburg │ 972│ 1,040│ 1,382│ 816│ 421│ 2│ ────────────────┼───────┼───────┼───────┼───────┼───────┼───────┼────── Total │176,331│185,617│177,467│157,731│157,178│119,789│78,681 ────────────────┴───────┴───────┴───────┴───────┴───────┴───────┴──────
Exports of crude platinum from Russia for the years 1911–15 were as follows[15] p. 923:
─────────────┬───────┬───────┬───────┬───────┬─────── To. │ 1911. │ 1912. │ 1913. │ 1914. │ 1915. ─────────────┼───────┼───────┼───────┼───────┼─────── Great Britain│ 1,053│ 2,107│ 1,580│ │ 66,884 France │168,527│169,580│140,615│ 64,778│ 7,900 Germany │ 51,612│ 50,558│ 58,458│ 17,906│ United States│ │ │ │ │ 5,266 ─────────────┼───────┼───────┼───────┼───────┼─────── Total │221,192│222,245│200,653│ 82,684│ 80,050 ─────────────┴───────┴───────┴───────┴───────┴───────
The platinum industry in Russia has always been mainly in the hands of a few large firms of foreign countries. For a long time Johnson, Matthey & Co., Ltd. controlled the greater part of the trade. In 1898 the Société Anonyme de l’Industrie du Platine was established in Paris, and, by purchasing a large number of mines, and leasing others, was able to secure a large share in the control of the industry.
The refining of the crude platinum has been, and still is, almost entirely in foreign hands, all but approximately 2 per cent. of the entire output being refined abroad. In 1915 it was reported that the construction of a refinery at Ekaterinburg was completed, which was to be placed under Government control. The principal platinum-refining works were formerly those of Johnson, Matthey & Co., Ltd., of England, but early in the eighties this firm was, to a certain extent, superseded by Heraeus & Co., of Hanau, Germany. They, in turn, in 1909, were compelled to give first place to the Société Anonyme de l’Industrie du Platine, of Paris, which became the chief centre of the platinum-refining industry, a position which it held until the outbreak of war. France at that time had a monopoly of 90 per cent. of the Russian production. This foreign control had an unfavourable effect on the industry, and in 1913 the Russian Government passed a law forbidding the exportation of crude platinum. In July 1915, exportation was again permitted, subject to a 30 per cent. _ad valorem_ export tax, and at about the same time an order was issued forbidding the exportation of raw platinum in quantities valued above 500 roubles (£53), the price of the metal to be fixed by the State[15] p. 923. In February 1917 the Government further enacted an order prohibiting the importation of drawn and spun platinum. It was hoped by these means to encourage the establishment of domestic refineries. In 1916 the Government fixed the price at £16 10s. per oz. In March 1917 it was reported that the miners were not satisfied, and later sales were reported up to £22 per oz. of crude metal, 83 per cent. fine[50] p. 17.
According to N. Vissotzki[51], the platiniferous belt of the Urals, geologically speaking, consists of four parallel bands striking, roughly, north and south; the westernmost of these, made up of crystalline schists, forms the watershed between Europe and Asia. The next band to the east comprises olivine- and mica-gabbros, diallage-peridotites, diorites and altered syenites—all of which have been erupted from a great depth. The third band is made up of Lower Devonian sedimentary rocks, shattered and buried in places by diabasic eruptive rocks. The eastern portion of this band is formed of eruptive rocks of deep-seated origin which may be gneissose granites. The fourth, or most easterly band, is composed of ancient rocks, which have been eroded by the advancing sea of Lower Tertiary age.
The area emerged from the waves as early as the Carboniferous period; consequently the accumulation of platinum, and in some localities of gold, in the surface-deposits, were not swept away. They were concentrated later on in the alluvia—perhaps at the time of the most intense glaciation, probably in the Pleistocene.
Throughout the Urals, the primary source of the platinum is associated with the eruptive basic rocks, among which the platiniferous and auriferous dunite forms three great masses. The principal outcrops of platiniferous dunite and platinum-bearing alluvia are connected with the second of the four parallel bands mentioned above. Towards the south, the band becomes discontinuous, and finally dies out altogether. Here a few outcrops of platiniferous olivine-rock contain a small percentage of platinum, with osmiridium and other members of the group associated with it.
The two principal platinum-producing districts are in the central Urals, and are: (1) The Shuvaloff Estates, Isov district, on the River Iss, near Goroblagodat. (2) The Demidoff Estates, Nizhni-Tagilsk district, on the Martian River in the South Verkhotur district. Prior to 1879 the latter field furnished the larger part of the platinum, but since then the former has been the most productive, and now supplies about 80 per cent. of the total output. The whole of the platinum is derived from gravel deposits, which are usually auriferous, and associated with dunite.
_The Isov district._—Platinum is concentrated in the channels of the Rivers Iss, Veeya and Tura. In the north of this region it is obtained from the Sosnovki, Kytlymi, and Mala Kosva Rivers; further north again, platinum occurs with gold in the Vagran River, and in the system comprising the Rivers Lobva, Niasma, Lialia, Aktai, Emerlo and Talits, the gold here being predominant. Other sources of supply of platinum and gold in this district are on the Ivdevl River. In the south of the area, platinum deposits are worked on the tributaries of the Tagil, Salda, Imiaun and Tura Rivers[15] p. 921.
_The Nizhni-Tagilsk district._—The richest placers occur in the valleys of the Visim, Martian, Sisim, Chaush and Cherna Rivers. Further south, platinum is found with gold in the gravels of the Nevian, Verkhne-Iset, Bilenibaev, Alapaev, Sysert, Kyshtym and Mias areas, and also in the Tanalyk, Sakmar and Urtazym Rivers.
Other localities of smaller importance are the Nikolae Pavdinsk and Rastes districts in the northern Urals, and the Systersk mining district.
The placers are derived from country rock, made up of serpentine gabbro, diallage and olivenite, the principal associated minerals being quartz, zircon, ilmenite, chromite, magnetite, spinel, native gold and palladium. Gold is present in the concentrate in very variable quantities, and sometimes contains silver, but the latter generally occurs in combination with palladium. The crude platinum usually includes some iridium, rhodium, ruthenium and iron.
The basic igneous rocks, from which the platinum is derived, are exposed in the form of discontinuous elliptical outcrops near the summits of the Urals, particularly on the western side of the mountains. These outcrops attain larger dimensions in the northern and central Urals than further south. The process of concentration of platinum in the gravels has clearly extended over a very long period of time, and it is probable that the richer gravels have been reconcentrated, perhaps several times[52] p. 299. Platinum nuggets are rarely found, but three of large size were discovered in the Nizhni-Tagilsk district, their weights respectively being 25½ lb., 21 lb., and 11½ lb.
Duparc, in a brief description of the geology of the deposits, states that they are essentially of magmatic origin. The structure of the rock is in the nature of concentric bandings; the felspathic rocks at the outer edge gradually grade into the intermediate stage of pyroxenes, until the central dunite is reached, composed of olivine and chromite. The richness of the gravels is in proportion to the size of the dunite deposits, and to the extent of erosion of these rocks. According to Duparc, platinum ore derived from a pyroxenite source usually contains high percentages of platinum and palladium, but low percentages of osmium and iron. The same writer estimated in 1916 that the reserves were sufficient for about twelve years, provided that the same methods of working and rate of extraction were employed during that period[53].
The amount of the platinum in the wash is very variable. The average yield was formerly over ½ oz. per c. yd., but latterly, owing to the gradual exhaustion of the richer deposits, the average returns have not exceeded from 2 to 3 dwt. per c. yd. The crude metal assays about 83 per cent. platinum, from 5 to 7 per cent. osmium and iridium, with small amounts of ruthenium, palladium, and gold, and about 10 per cent. impurities, mostly iron and copper[54]. The thickness of the pay gravels varies from 3 to 6 ft., and about 4 ft. may be taken as the average width, the overburden running from a few to over 60 ft. The extent of the productive area is about 170 sq. miles, and from 15,000 to 20,000 miners were employed before the war[4] p. 558. It has been noticed that the platinum deposits are characterized by their uniformity, of course not being so sinuous in direction as gold deposits.
In former times mining was entirely carried on by primitive methods with hand labour, but the utilization of dredges has steadily increased, since their introduction in 1900. In 1909, 13 per cent. of the total production was obtained by dredging, and in 1914 this percentage rose to one-third of the total output. The season during which dredges may be employed extends on the average from the middle of April to the middle of October. In the South Verkhotur and Perm areas dredges have been used in the large enterprises; but at the small mines the working is very primitive, and carried on largely with the help of _starateli_, or tributers. In 1914 a modern 7½ c. ft. dredge was installed on the Nikolaie-Pavdinsk Estate.
In mines where dredging is not in use, the gravels are mined by open cuts, or, if the overburden is thick, shafts are employed. The former method is much preferred, both on account of its relative cheapness, and also because it is possible to obtain a better clean-up of the bedrock.
The usual types of stationary plant in use include the _botchka_, or conical revolving screen; the _tchaska_, or puddling machine, with a bottom of perforated iron plates; and the _boronka_, or conical screen, on which the stones and clay are turned over by a double rake[55]. The gold is removed by amalgamation with mercury in wood, iron or porcelain bowls. Special methods are in use in certain parts of Russia for working the deposits during the winter. The workings are allowed to freeze, and the frozen ground is mined after being partially thawed by means of wood fires. The method is simple, but care must be taken to ensure that the thawing does not proceed too far, otherwise the ground collapses, and the workings become flooded. The method is suitable for depths to 30 ft., and in localities where the snowfall is comparatively slight.
Latest reports from Russia indicate that no dredges are now working there, the platinum being produced by hand methods only.
Some interesting experiments were recently carried out by V. N. Chorzhevski in the Nizhni-Tagilsk district, with a view to testing the commercial possibility of mining platinum _in situ_. The metal here occurs, in association with chrome iron ore, in dunite rock, which in this region extends over an area of 11½ sq. miles. The platinum appears to be present in quantities directly proportional to the amount of chromite in the rock. The dunite is first ground under runners; the chromite slack is separated from it; and after this has undergone a second grinding, the metal is separated by washing[56]. An experimental test, carried out in March 1917, is stated to have produced over 200 oz. platinum from 9,720 lb. chromite slack. Another experiment with 3,600 lb. of grey slack, “or fines,” consisting chiefly of undecomposed dunite obtained from the dredges, is reported to have yielded ⅓ oz. of platinum.
_Lapland._—Platinum occurs associated with chromite and diamonds, in alluvial deposits on the Ivalo River. It is believed to be derived from serpentine rock, of which the neighbouring country is largely composed[4] p. 556.
_Finland._—Platinum has been found in the south in a lode-formation containing quartz, siderite, calcite and dolomite. Gold and carbonate of copper are also present in small quantities.[4] p. 557.
PLATINUM CURRENCY
In a dispatch to the Great Powers on February 26, 1920, the Soviet Government promised to withdraw the decree annulling Russia’s foreign debt, to pay arrears of interest, and giving as a guarantee to an Anglo-American syndicate certain important platinum and silver-mining concessions, in return for which the abandonment of intervention in Russia’s internal affairs was demanded. To be used in payment of foreign purchases, the Government was about to issue “platinum” credit notes of 50, 100, 500, and 5,000 roubles, the issue to be limited to 65,000,000 roubles, and backed by platinum reserves of 37,500,000 roubles. The Government would be ready to convert the platinum reserves into coin if required[57].
SPAIN
Promising deposits of platinum have recently been reported at Ronda, in the province of Malaga. Domingo de Orueta, a Government geologist, having noticed the similarity of the geology of this district to that of the platiniferous deposits of the Urals, proceeded, a few years ago, to explore the area systematically, and was soon rewarded, in the discovery of the metal. The deposits, which are alluvial, extend along the Verde and Guadaiza rivers, and are derived from serpentine and peridotite rocks, the latter composed principally of rhombic pyroxene, with some spinel and some dunite. Chromite occurs in association with the platinum. The pay gravels contain about 8 gr. platinum per ton, and are stated to have an average thickness of 5 ft., the depth of overburden in the Guadaiza area, where apparently the richer gravels are found, being about 33 ft., as compared with 49 ft. in the Verde locality[10] p. 547. The Spanish Government have taken over the exploitation of these deposits, and no public prospecting, without Government permission, is allowed.
Platinum is known to exist in a number of other localities in Spain, especially in the northern districts; but so far as is known, it occurs in very small quantities of no commercial importance. The metal has been recognized in the following rivers: Minho, Luna, Sil, Orbigo, Gallego, Cinca Darro and Lower Jenil, where it occurs in the concentrate sands, accompanied by magnetite, ilmenite, zircon and, frequently, gold[58].
ASIA
ARMENIA
Platinum, in association with gold, is reported to occur in the district of Batum and Sasun, on the Charokh River[46] p. 610.
BORNEO
Platinum was discovered in south-eastern Borneo in 1831, in the gravels of Gunung Lawack, but for a long time the natives were ignorant of its value. In recent years it has been obtained on a small scale as a by-product in the process of gold-washing, carried on in the province of Tanah-Laut, in the south-eastern extremity of the island[59]. The deposits occur in streams, which rise in the Bobaris Mountains, where the country rocks are composed of schists and gneisses, intruded by serpentine gabbro and diorite dykes[52] p. 298. Platinum has, however, not yet been located _in situ_. In addition to gold, the platinum is associated with osmiridium in the gravels, the two former being frequently found intimately intergrown. The platinum content of the native metal has been found by a number of analyses to vary from about 57 to 83 per cent., and that of osmiridium from 0·18 to 10·07 per cent.[60].
The rare mineral _laurite_, a sulphide of ruthenium and osmium, was discovered in these deposits.
According to L. Hundeshagen[61], the platinum occurring in the diamond placers of western and south-eastern Borneo is in the form of thin scales, ranging from 0·1 to 1·0 mm. in length. These platinum scales contain from 3·8 to 4·5 per cent. of copper, evidently as an alloy.
CHINA
In the Uryanchai district of Mongolia, situated on the Russian border, deposits of auriferous gravels have been worked on a fairly extensive scale for some time past. It was announced a few years ago that platinum and iridium had been found in appreciable quantities, associated with the gold, some large platinum nuggets being obtained from this region in 1911. Although no attempt at commercial development has yet been made, the prospects of profitable extraction appear to be hopeful. Extensive outcrops of olivine rocks have been noticed in the vicinity, and the nature of the occurrence is stated to bear some resemblance to that of the platiniferous fields of the southern Urals[8] p. 107.
JAPAN
Platinum occurs in the Yubari-garva, Pechau and other rivers in the province of Hokkaido. It is also found in Nishi-Mikawa, province of Sado. In the former locality gold and iridosmine are associated with the platinum, and in the latter gold and iron sands are present[62]. In no case has the metal been traced to its parent source. In the Hokkaido deposits the average quantity of platinum present is only 2 or 3 per cent. of the iridosmine content. It is possible that further exploration in these areas will reveal occurrences of greater importance[9] p. 597.
SUMATRA
Platinum is obtained at Sipongi, where it occurs with wollastonite and grossularite in limestones and schists, near intrusions of granodiorite and augite diorite. Gold is also present.
L. Hundeshagen[61] is of opinion that the present ore deposit was originally a layer, or a big lens, of limestone embedded in the old schists, which has, by apophyses of granite, been altered into garnet and wollastonite, being at the same time, or very soon afterwards, mineralized by hot solutions carrying copper, gold, platinum, etc. A sample of slightly decomposed wollastonite with no copper, or only minute traces of that metal, proved to be richest in platinum, the assay showing 6 gm. of platinum per 1,000 kg., while samples with 2 to 10 per cent. of bornite and malachite contained only traces of platinum; and none could be detected in auriferous garnet, poor in wollastonite. About 10 to 25 metres from the outcrop the concentrated river sand shows small particles of whitish crystalline gold and rounded grains of white platinum, the latter varying from 0·1 to 0·3 mm. in size.
AFRICA
CONGO FREE STATE
In the Katanga district, platinum and palladium have been reported to occur in certain alluvial gravels, accompanied by gold and silver. One sample from this locality is stated to have yielded the following amounts per metric ton: 3·4 gr. platinum, 12·3 gr. gold, 8·3 gr. silver. It has also been located _in situ_ in sandstones containing gold.
MADAGASCAR
Platinum is produced on a small scale as a by-product in alluvial gold mining on the Vatana River, near the village of Ambia, in the Vatomandry district. Traces of the metal have also been found in auriferous gravels in the regions of Fenerive, Marolambo, and Vandrozo, over an area extending along the eastern side of the island for a length of about 450 miles. The platinum is apparently derived from the decomposition of pegmatite. It is rarely found pure, being usually coated with iron oxide, and strongly magnetic, a property which is utilized in the process of separation from the gold[63].
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 ───────────────┴────────┴──────┴──────┴──────┴──────┴──────┴──────┴──────
Footnote 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.
SOUTH AMERICA
BRAZIL
José Vieira do Couto, in 1801, first pointed out that platinum occurs in the sands of the Lages River, near Conceiçao, Minas Geraes. According to E. Hussak[78], platinum in that region occurs only in the alluvium of rivers having their rise on the eastern slope of the Serra do Espinhaço. The platinum is accompanied by black pebbles of quartz-tourmaline rocks, magnetite, hematite, rutile, octahedrite, xenotime, monazite, senaite, pseudomorphs of rutile after octahedrite (_captivos_), zircon and gold, which is sometimes of a copper-red colour (palladium-gold). Palladic gold was formerly called _ouro branco_ (white gold), by the miners.
At Condado, further north on the eastern slope of the same Serra, platinum also occurs with very similar associations. The platinum from both localities occurs in bunchy, mammillated and globular forms, concave within, with thin walls, having a radiated fibrous structure under the microscope. It is frequently in thin foliated crusts, having the characteristic structure of hematite. It was accurately described by Wollaston in 1805 and 1809. Hussak thinks the primary formation was an olivine rock, or gabbro, while the platinum is secondary, having been most probably re-deposited from solutions resulting from the decomposition of platiniferous pyrites or of sperrylite (PtAs_{2}), minerals derived, possibly, from the neighbouring schistose quartzite, or from the overlying conglomeratic quartzite.
The platinum of Condado, although comparable, as regards density, to the Russian platinum, is very rich in palladium, is non-magnetic and contains practically no iron. An analysis by G. Florence gave the following percentages: insoluble residue, 0·92; platinum, 73·99; iridium, 0·08; palladium, 21·77; iron, 0·10 (= 96·86), undetermined (rhodium and osmium), 3·14.
In the Rio Abaeté, Minas Geraes, platinum—very different in appearance and chemical composition from that of the Serra do Espinhaço—occurs in placer deposits, associated with gold, diamonds and the following minerals: rolled pieces of a hydro-phosphate of barium and aluminium (_gorceixite_ = “marumbé” of miners), garnet, almandite, pyrope, ashy-blue oxide of titanium (_bagageira_—regarded as a good indicator for diamonds), magnetite, chromite and calcium-titanate (_perovskite_). Pyroxene-olivine rock, a typical picrite-porphyry, rich in perovskite, and granular magnetite rocks, rich in titanium, have been observed by Oliveira in the vicinity. Hence it is highly probable that the platinum, as in the Urals, came from olivine rocks. The platinum occurs in thin laminæ, strongly rolled, and, rarely, in cubical crystals with the edges visibly rounded. It is strongly magnetic and contains no palladium. Minute crystals of osmiridium may occur with those of platinum, and in the platinum particles are found regular inclusions of osmiridium, as at Nizhne Turinsk, in the Urals, the platinum of which locality it resembles in chemical composition, magnetic properties and crystalline structure. The following analysis shows the percentage and composition of a general sample: insoluble residue, 7·57; iron, 9·62; palladium, trace; copper, trace; platinum metals, 82·81.
The auriferous alluvial of the Cuyabá and Coxim rivers in the southern part of the State of Matto-Grosso, also contain some platinum. According to Luiz Caetano Ferraz[79], platinum occurs in the River Coxipó-Mirim, where golddredging is carried on, combined with palladium, iron, osmium and iridium in small spherical grains, flattened on one side, of a brilliant white colour and strongly magnetic. It is found in alluvial deposits, associated with various kinds of quartz and oxides of iron, marcasite, arsenopyrite, rutile, anatase, almandine, garnet, black tourmaline, monazite, staurolite, white topaz, sphene, cassiterite, wolfram, graphite, galena and native silver.
In the State of Bahia, platinum has been found in Ituassú, Feira de S. Anna and Serra do Assuruá, and it is said to occur at Sâo Bartholomeu, and in the Serras do Pitango and Macahubes[80].
Platinum also occurs in Brazil as rare disseminations in the gold-bearing _jacutinga_, intercalated in the itabirites (e.g. at Gongo Socco Mine, long since abandoned). The jacutinga occurs as narrow bands and nuclei in the itabirites, containing a high percentage of gold, with much talc, clay and pulverulent pyrolusite. As accessory minerals zircon, rutile, cassiterite and tourmaline occur. Hussak thinks that the gold-bearing jacutinga has been derived from altered pegmatite veins.
From analyses made by Johnson (1833–41) on the Gongo Socco bullion, it would appear that the percentages of silver and platinum decreased while those of copper and palladium increased with depth (Henwood). The percentages of palladium varied from 3·89 to 4·80, and that of platinum from 0·04 to 0·12.
At Candonga, gold occurs in an eruptive rock rich in magnetite enclosed in itabirite, and is probably of contact-metamorphic origin. The gold occurs in grains of high standard, and with it are found fine indented scales of palladic gold, of a bright copper-red colour.
At Itabira do Matto Dentro gold occurs in jacutinga, lying between a micaceous iron schist, rich in quartz, and an enormous solid bed of itabirite. The palladium-gold may be copper-red, dark-brown or silver-white in colour. Native platinum also occurs with the gold.
Grains of platinum have also been found in the most northerly of the auriferous lenticular masses, which occur near the Bruscus River, near Pernambuco, in Cambrian crystalline schists. The matrix is a coarse white quartz containing small quantities of the arsenides and sulphides of iron, and the sulphides of copper, lead and zinc.
Platinum, although widely distributed in Brazil, occurs in such small quantities that so far there has been no production; but in the near future richer and more extensive deposits may be discovered, or it may be found practicable to win the metal from those already known, as an important by-product.
Palladium-gold, or _porpezite_, is a natural alloy of palladium and gold, and may contain up to 10 per cent. of the former metal. It is found in Brazil, in gold-washings, and also in the gold-bearing jacutinga reefs at Gongo Socco, Candonga and Itabira do Matto Dentro. In 1870 Henwood showed that the palladic gold from Gongo Socco contained, to a moderate depth from surface, from 0·04 to 0·12 per cent. of platinum. (Palladium-gold has also been reported from gold-washings in the Caucasus, near Batoum.) Ruer concludes, from an examination of the freezing-point curves of artificial alloys of gold and palladium, that these alloys form a continuous series of mixed crystals, and that there is no indication of chemical combinations[81].
COLOMBIA
This republic is the second largest producer of platinum in the world, and in pre-war years supplied about 5 per cent. of the world’s total output. Owing to the decline of the Russian supply, and the increased demand for the metal, the industry has in recent years received a considerable stimulus, and in 1916 Colombia’s production rose to approximately one-third of the Russian output.
Platinum was first introduced into Europe from Colombia in 1735, although the metal was known in America for some time previously[48] p. 608. In 1810 the value of platinum stood at $5 to $6 (U.S.) per oz., and in 1823 the price had further dropped to from $3 to $4 per oz. As a result, platinum was rejected as waste in the operation of refining gold by the “dry-blowing” system. Later, when platinum became valuable, much of this dumped metal was recovered, notably in Quibdo, the capital of the Chocó district, where much gold-refining was carried on.
The following table gives the outputs of crude platinum from Colombia, in recent years, principally produced in the Chocó district:
Year. Oz. (troy).
1911 12,000 1912 12,000 1913 15,000 1914 17,500 1915 18,000 1916 25,000 1917 32,000 1918 35,000 (estimated)
The larger portion of the production is shipped to the United States, the exports to that country for the years 1910–18 being as follows:
Year. Oz. (troy).
1910 1,600 1911 5,503 1912 6,627 1913 10,461 1914 12,387 1915 13,121 1916 25,588 1917 21,278 1918 27,030
The crude platinum is estimated at 84 to 85 per cent. fine. The price in 1917 fluctuated from £16 to £20 10_s._ per oz., the average for the year being nearer the latter amount.
During 1918 the United States Government fixed the price at $105 per oz., which stimulated production.
The deposits are alluvial, and consist of re-concentrates of older gravels. The principal source of supply is at the head of the San Juan River, which enters the Pacific Ocean north of Buenaventura, the richest deposits occurring in the Condoto, Opagado and Tamanal Rivers, tributaries of the San Juan[82]. Platinum is also obtained in the Upper Atrato River, which flows northward to the Caribbean Sea. It is nearly always found associated with gold. In the gravels of the San Juan River the two metals are present in about equal proportions, and in those of the Atrato the ratio is approximately 85 of gold to 15 of platinum.
The area including the watersheds of the San Juan and Upper Atrato Rivers is known as the Chocó district. T. Ospina, Director of the Colombian School of Mines[83], estimates that in the area are 5,000 sq. miles of gold and platinum deposits, the Mira River forming the southern boundary of the area. In 1916 he estimated that there were in it 68,000,000 c. yd. of actually profitable gravel, with a reserve of 336,000,000 yd. of possibly profitable ground. Platinum has also been recovered in much smaller amounts on the Micay River in the Barbacoas district, near the frontier of Ecuador. The stream beds in which platinum occurs are those in which Tertiary conglomerates have become eroded; the river gravels about the areas underlain by that formation are barren. The conglomerates are composed of rounded boulders of basic rocks, such as diabase, melaphyre, peridotite and dunite[48] p. 620.
At Novita Vieja, in the centre of the Chocó district, a bed of conglomerate 6 to 12 ft. thick has been laid bare, over an area 2½ miles long and ½ mile wide, through the sluicing away of the overlying sands. It contains 0·5 oz. of gold, and 0·5 oz. of platinum, per ton[84]. According to Castillo, the parent rock is a typical gabbro, pyroxene predominating over the felspar[85] p. 826.
Platinum has been found in the Chocó district in serpentine rock. Granite also occurs in the same district, traversed by quartz lodes containing palladium, iridium, osmium and rhodium.
Colombian crude platinum contains from 80 to 85 per cent. platinum, the remaining 15 to 20 per cent. consisting chiefly of iridium and osmium. The sands in which it occurs are described as brown in colour, and carrying, besides platinum and gold, the heavy minerals chromite, magnetite and ilmenite [85] p. 384.
In the past, mining operations have been very irregularly carried on, by primitive methods of working, but dredges are now being employed in increasing numbers. In 1915 a dredge was operated on the Condoto River, in the province of Chocó, by the Anglo-Colombian Development Company, and showed good results. Native methods of working are very simple. The alluvial gravels derived from dried-up beds of ancient rivers are hand-washed with the use of the _batea_ or dish. Where the metal occurs in the bed of a river it is obtained by diving girls, who work down to the platiniferous gravels, removing the gravel in small dishes, the men being employed in washing the gravels on the river banks[86]. About 90 per cent. of the total output is recovered by these primitive methods.
A large portion of the industry is in the hands of two companies, one of which is the South American Gold and Platinum Company, of New York, a Lewisohn company, which has absorbed the interests of the above-mentioned Anglo-Colombian Development Company, Ltd., the Gold Fields American Development Company, Ltd., and Johnson, Matthey & Co., Ltd., of London. The second company—the British Platinum and Gold Corporation, Ltd.—has recently amalgamated with the Paris (Transvaal) Gold Mines, Ltd., taking in the latter’s interests on the Opogodo and other places.
The question of transporting platinum concentrate to the coast is not a matter of much difficulty, as the Atrato River is navigable as far as Quibdo, and the San Juan can be ascended by vessels of moderate draught for over 140 miles inland.
An estimate of average working costs appears to be 6_d._ per c. yd. for dredging, and 3_d._ for hydraulicking[87]. In 1917 new platiniferous deposits were discovered in the Caceres district, between the Cauca and Nechi Rivers, in the department of Antioquia. The mineralized area extends along the Caceri River, a distance of 14¼ miles, the width at the north end being 1¼ miles, and 300 ft. at the southern extremity [10] p. 545.
ECUADOR
Platinum occurs, in association with the gold obtained from steam gravels, in the area covered by the Rivers Bogota, Cachabi, Uimbi, Santiago and Cayapas, but it has not so far been found in sufficient quantities to be of economic importance.
Dredging has been employed in mining these deposits, but does not appear to have been a success, and operations are now largely confined to native washings[88].
FRENCH GUIANA
Platiniferous gold-bearing sands are found in the Aporuague River, the metal, according to an analysis by A. Danmer, having the following composition in percentages: platinum, 41·96; gold, 18·18; silver, 18·39; copper, 20·56[89].
WORLD MAP OF PLATINUM DEPOSITS
REFERENCES TO LITERATURE ON THE PLATINUM METALS
Footnote 1:
Lindgren, W.: “Platinum and Allied Metals,” _U.S. Geol. Surv., Min. Res. of U.S._, 1911.
Footnote 2:
Thomas and MacAlister: _The Geology of Ore Deposits_, London, 1909.
Footnote 3:
Gowland, W.: _Metallurgy of Non-Ferrous Metals_, London, 1918.
Footnote 4:
Dunstan, B.: _Queensland Govt. Min. Journ._, 1917, =18=.
Footnote 5:
Lindgren, W.: “Platinum and Allied Metals,” _U.S. Geol. Surv., Min. Res. of U.S._, 1910.
Footnote 6:
Rose, T. K.: “Electrolytic Refining of Gold,” _Trans. Inst. Min. and Met._, 1914–15, =24=, p. 45.
Footnote 7:
Hill, Jas. M.: “The Platinum Situation,” _Eng. Min. Journ._, July 26, 1919.
Footnote 8:
Hautpick, E. de: _Mining Journ._, Feb. 1, 1913.
Footnote 9:
_Mineral Industry_, 1916, =25=.
Footnote 10:
_Mineral Industry_, 1917, =26=.
Footnote 11:
_Review of Foreign Press, Technical Supplement_, War Office, May 27, 1919, p. 395.
Footnote 12:
_Mining Journ._, Dec. 27, 1919.
Footnote 13:
_Chem. and Met. Eng._, Oct. 15, 1918, p. 607.
Footnote 14:
Hill, Jas. M.: “Platinum Deposits of the World,” _Eng. Min. Journ._, June 30, 1917.
Footnote 15:
Merz, A. R.: _Journ. Ind. and Eng. Chem._, Nov. 1918, =10=, No. 11.
Footnote 16:
_Annual Statements of Trade of the United Kingdom._
Footnote 17:
Spurr, J. E.: “Who Owns the Earth?” _Eng. Min. Journ._, Feb. 7, 1920.
Footnote 18:
_Records Geol. Surv. of India_, 1916, =47=, pt. 3, p. 163.
Footnote 19:
_Records Geol. Surv. of India_, 1919, =50=, pt. 3, p. 156.
Footnote 20:
_Records Geol. Surv. of India_, 1915, =46=, p. 284.
Footnote 21:
Zealley, A. E. V.: _South Rhod. Geol. Surv., Short Rept._ No. 3, March 20, 1918.
Footnote 22:
_Bull. Imp. Inst._, 1907, =5=, p. 137.
Footnote 23:
“Geology of the Selukwe Mineral Belt,” _Geol. Surv. Bull. South Rhod._, 1919, No. 3, p. 65.
Footnote 24:
Versfield, W.: Rept. on Metal Resources of Union of S. Africa, 1918.
Footnote 25:
Goodchild, W. H.: _Trans. Inst. Min. and Met._, 1916–17, =26=.
Footnote 26:
Bettel, W.: _S. African Mines_, Nov. 10, 1916.
Footnote 27:
Hall, A., and Humphrey, W. A.: “The Chromite Deposits of the Bushveld Plutonic Complex,” _Trans. Geol. Soc. S. Africa_, 1908, =11=, pp. 75–6.
Footnote 28:
_Mining Journ._, Feb. 29, 1913.
Footnote 29:
Mackenzie, G. C.: _Can. Min. Inst. Bull._, April 1919.
Footnote 30:
Camsell, C.: _Mining Journ._, May 1914, p. 523.
Footnote 31:
Uglow, W. L.: “Geology of Platinum Deposits,” _Eng. Min. Journ._, Aug. 30, 1919; Sept. 6, 1919.
Footnote 32:
_Chem. Trade Journ._, 1911, =49=, p. 271.
Footnote 33:
_Min. Sci. Press_, April 10, 1920, p. 536.
Footnote 34:
_Board of Trade Journ._, 1917, =99=, p. 156.
Footnote 35:
_Can. Min. Journ._, 1916, =37=, p. 548.
Footnote 36:
_Can. Min. Inst. Bull._, 1918, No. 63, p. 99.
Footnote 37:
_Geol. Surv. of Canada, Min. Res. of Canada_, 1903, No. 818.
Footnote 38:
_Board of Trade Journ._, April 17, 1919, p. 504.
Footnote 39:
Howley, G. P.: _Mining World_, 1907, =26=, p. 783.
Footnote 40:
_N.S.W. Dept. of Mines, Ann. Rept. for 1918_, p. 52.
Footnote 41:
_N.S.W. Dept. of Mines, Ann. Rept. for 1915_, p. 59.
Footnote 42:
Hill, Jas. M.: “Platinum and Allied Metals in 1916,” _U.S. Geol. Surv._, July 12, 1917.
Footnote 43:
_Rec. of Geol. Surv. N.S.W._, 1916, =9=, pt. 3, p. 127.
Footnote 44:
_Min. and Sci. Press_, April 10, 1919.
Footnote 45:
Bell, G. M.: _Economic Geology_, 1906, =1=, No. 8, p. 749.
Footnote 46:
_Mineral Industry_, 1914, =23=.
Footnote 47:
Krusch, P.: “The Platinum Deposits of Germany’s Palæozoic” (trans. by F. S. Schmidt), _Min. and Sci. Press_, 1914, =109=, p. 880.
Footnote 48:
_Pan-American Union_, 1917, =45=.
Footnote 49:
_Mining Journ._, 1904, =76=, p. 597.
Footnote 50:
Hill, Jas. M.: “Platinum and Allied Metals in 1917,” _U.S. Geol. Surv., Min. Res._, 1917, pt. 1, p. 11.
Footnote 51:
Vissotzki, N.: _Bull. du Comité géologique_, St. Petersburg, =22=, 1903 (abstract in _Trans. Inst. M.E._, 1903, =27=, p. 660).
Footnote 52:
Hill, G. M.: _U.S. Comm. Repts._, 1917, No. 94.
Footnote 53:
Duparc, L.: _Soc. Ings. Civils, France, Mem. 1916, Bull._ Janv.-Mars.
Footnote 54:
Ball, S. H., and Low, B.: _Eng. and Min. Journ._, March 10, 1917, p. 407.
Footnote 55:
Tovey, L.: _Eng. and Min. Journ._, Oct. 10, 1908, p. 704.
Footnote 56:
_Chem. Trade Journ._, 1917, =60=, No. 1,562, p. 362.
Footnote 57:
_Eng. and Min. Journ._, Mar. 6, 1920.
Footnote 58:
_Mineral Industry_, 1915, =24=, p. 580.
Footnote 59:
Posewitz, T.: _Geology and Mineral Resources of Borneo_, 1892 (trans. by F. H. Hatch).
Footnote 60:
_Mineral Industry_, 1913, =22=, p. 597.
Footnote 61:
Hundeshagen, L.: “The Occurrence of Platinum in Wollastonite, Sumatra, N.E.I.,” _Trans. Inst. Min. and Met., 1903–4_, =13=, p. 550–2.
Footnote 62:
Wada, Tsumashire: _Minerals of Japan_, 1904, p. 89 (trans. by Takudgi Okawa).
Footnote 63:
_Bull. Econ. de Madagascar_, 1912, No. 2, p. 86.
Footnote 64:
Hautpick, E. de: _Min. Journ._, July 27, 1912, =98=, p. 747.
Footnote 65:
_Mineral Industry_, 1918, =27=, p. 571.
Footnote 66:
_Eng. and Min. Journ._, Jan. 11, 1919, p. 107.
Footnote 67:
Mertie, J. B., Jr.: “The Salt Chuck Palladium-Copper Mine,” _Eng. and Min. Journ._, July 3, 1920.
Footnote 68:
Martin, Johnson and Grant: _U.S. Geol. Surv., 1917_, _Bull._ No. 587, p. 238.
Footnote 69:
Campbell, Donald G.: “Palladium in Alaskan Lode Deposits,” _Min. and Sci. Press_, Oct. 11, 1919.
Footnote 70:
_Board of Trade Journ._, Dec. 11, 1919, =103=.
Footnote 71:
_Min. and Sci. Press_, Mar. 15, 1919, p. 367.
Footnote 72:
Hall, F. A.: _Eng. and Min. Journ._, Oct. 10, 1914, p. 642.
Footnote 73:
Knopf, A.: _Min. and Sci. Press_, June 5, 1915, p. 878.
Footnote 74:
_Chem. and Met. Eng._, March 24, 1920.
Footnote 75:
_Min. and Sci. Press_, March 9, 1920.
Footnote 76:
_Eng. and Min. Journ._, May 25, 1905, p. 985.
Footnote 77:
Taft, H. H.: _Eng. and Min. Journ._, 1918, =106=, No. 21, p. 900.
Footnote 78:
Hussak, Euginio: “O Palladio e a Platina no Brasil,” _Annas da Escola de Minas de Ouro Preto_, 1916, No. 8, 85–188.
Footnote 79:
Ferraz, Luiz Caetano: _Annas da Escola de Minas de Ouro Preto_, 1909, No. 11.
Footnote 80:
Carneiro, A. J. de Sousa: _Riquezas Mineraes do Estado da Bahia_, 1908.
Footnote 81:
Maclaren, J. M.: _Gold: Its Geological Occurrence and Geographical Distribution_, London, 1908, p. 25.
Footnote 82:
_Journ. of the Royal Society of Arts_, 1908, =56=, p. 884.
Footnote 83:
Ospina, T.: Paper read before second Pan-American Congr., Jan. 3, 1916.
Footnote 84:
White, R. W.: _Eng. and Min. Journ._, 1897, =63=, p. 189.
Footnote 85:
Castillo, J. C.: _Min. and Sci. Press_, 1909, =98=.
Footnote 86:
“Platinum-seeking in Colombia,” _The Times_, Nov. 26, 1912.
Footnote 87:
_Mining Journ._, Nov. 30, 1918, p. 700.
Footnote 88:
Millar and Singewald: _Mineral Deposits of South America_, New York, 1919, p. 405.
Footnote 89:
Kunz, George F.: “Platinum and Palladium in Brazil,” _Pan-American Bull._, April 1919, p. 408.
Footnote 90:
_U.S. Comm. Repts._, 1919, No. 21, p. 387.
PRINTED BY HAZELL, WATSON AND VINEY, LD., LONDON AND AYLESBURY, ENGLAND.
TRANSCRIBER’S NOTES
1. Footnote [90] (was 64) was unanchored. 2. P. 59, added missing title “WORLD MAP OF PLATINUM DEPOSITS.” 3. Silently corrected typographical errors and variations in spelling. 4. Archaic, non-standard, and uncertain spellings retained as printed. 5. Footnotes were re-indexed using numbers and collected together at the end of the last chapter. 6. Enclosed italics font in _underscores_. 7. Enclosed bold font in =equals=. 8. Subscripts are denoted by an underscore before a series of subscripted characters enclosed in curly braces, e.g. H_{2}O.