IMPERIAL INSTITUTE MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE TN BRITISH EMPIRE PREPARED UNDER THE DIRECTION OF THE MINERAL RESOURCES COMMITTEE OF THE IMPERIAL INSTITUTE, WITH THE ASSISTANCE OF THE SCIENTIFIC AND TECHNICAL STAFF THE PLATINUM METALS BY A. D. LUMB, A.R.S.M., F.G.S., Assoc. Inst. M.M LATELY OF THE SCIENTIFIC AND TECHNICAL DEPARTMENT, IMPERIAL INSTITUTE UC-NRLF LONDON JOHN MURRAY, ALBEMARLE STREET, W 1920 Price 3s. 6d. net IMPERIAL INSTITUTE MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE IMPERIAL INSTITUTE MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE PREPARED UNDER THE DIRECTION OF THE MINERAL RESOURCES COMMITTEE WITH THE ASSISTANCE OF THE SCIENTIFIC AND TECH- NICAL STAFF OF THE IMPERIAL INSTITUTE THE PLATINUM METALS BY A. D. LUMB, A.R.S.M., F.G.S., Assoc. Inst. M.M, LATELY OF THE SCIENTIFIC AND TCHNICAL DEPARTMENT, IMPERIAL INSTITUTE WITH A MAP LONDON JOHN MURRAY, ALBEMARLE STREET, W. 1920 ALL RIGHTS RESERVED IMPERIAL INSTITUTE MINERAL SECTION THE Imperial Institute is a centre for the exhibition and investigation of minerals with a view to their commercial development and for the supply of information respecting the sources, composition and value of minerals of all kinds. The Imperial Institute is provided with Research Labora- tories for the investigation, analysis and assay of minerals, and undertakes reports on the composition and value of minerals, for the information of Governments and producing companies and firms, in communication with the principal users in the United Kingdom and elsewhere in the Empire. Important minerals from within the Empire are exhibited in the respective Courts of the Public Exhibition Galleries, and also in the Mineral Reference Collections of the Institute. A special staff is engaged in the collection, critical revision and arrangement of all important information respecting supplies of minerals especially within the Empire, new methods of usage and other commercial developments. Articles on these and related subjects are periodically published in the Bulletin of the Imperial Institute, and mono- graphs on special subjects are separately published under the direction of the Committee on Mineral Resources. 448395 IMPERIAL INSTITUTE Advisory Committee on Mineral Resources The Right Hon. VISCOUNT HARCOURT, D.C.L. (Chairman). * Admiral SIR EDMOND SLADE, K.C.V.O., K.C.I.E. (nominated by the Admiralty), (Vice-Chairman). EDMUND G. DAVIS, Esq. *WYNDHAM R. DUNSTAN, Esq., C.M.G., LL.D., F.R.S., Director of the Imperial Institute. J. F. RONCA, Esq., M.B.E., A.R.C.S., Department of Industries and Manufactures (nominated by the Board of Trade). *Professor J. W. GREGORY, F.G.S., Professor of Geology, University of Glasgow, formerly Director of Geological Survey, Victoria, Australia. Sir ROBERT HADFIELD, Bart, F.R.S., Past-President Iron and Steel Institute. Captain A. L. ELSWORTHY, Intelligence Department, War Office (nominated by the War Office). W. W. MOYERS, Esq. (Messrs. A. Watson & Co.), Liverpool. R. ALLEN, Esq., M.A., B.Sc., Imperial Institute (Secretary). ' * Members of Editorial Sub-Committee MINERAL SECTION Principal Members of Staff Superintendent R. ALLEN, M.A. (Cantab.), B.Sc. (Lond.), M.Inst.M.M. Assistant Superintendent S. J. JOHNSTONE, B.Sc. (Lond.), A.I.C. Senior Assistants G. M. DAVIES, M.Sc. (Lond.), F.G.S. W. O. R. WYNN, A.I.C. Assistants S. BANN. A. T. FAIRCLOTH. F. H. BELL. R. C. GROVES, M.Sc. (Birm.). H. BENNETT, B.Sc. (Lond). E. HALSE, A. R.S.M., M.Inst.M.M. vi PREFACE THE Mineral Resources Committee of the Imperial Institute has arranged for the issue of this series of Monographs on Mineral Resources in amplification and extension of those which have appeared in the Bulletin of the Imperial Institute during the past fifteen years. The Monographs are prepared either by members of the Scientific and Technical Staff of the Imperial Institute, or by external contributors, to whom have been available the statistical and other special information relating to mineral resources collected and arranged at the Imperial Institute. The object of these Monographs is to give a general account of the occurrences and commercial utilisation of the more important minerals, particularly in the British Empire. No attempt has been made to give details of mining or metallur- gical processes. HARCOURT, Chairman Mineral Resources Committee. IMPERIAL INSTITUTE, LONDON, S.W.y. July 1920. vtt CONTENTS CHAPTER I PAGE THE PLATINUM METALS: THEIR OCCURRENCES, CHARACTERS AND USES. WORLD'S OUTPUT I CHAPTER II SOURCES OF SUPPLY OF PLATINUM METALS (a) BRITISH EMPIRE : . . . . . . .16 Europe : United Kingdom. Asia : India (Burma). Africa : Rhodesia ; Union of South Africa. America : Canada ; Newfoundland. Australasia : Australia ; New Zealand. CHAPTER III SOURCES OF SUPPLY OF PLATINUM METALS (b) FOREIGN COUNTRIES : 32 Europe : France ; Finland ; Germany ; Lapland ; Russia ; Spain. Asia : Armenia ; Borneo ; China ; Japan ; Sumatra. Africa : Congo Free State ; Madagascar. America : Brazil ; Colombia ; Ecuador ; Mexico ; United States. WORLD MAP OF PLATINUM DEPOSITS . . . -59 REFERENCES TO LITERATURE ON THE PLATINUM GROUP 60 NOTE. Numerals in square brackets in the text, rtfer to, the Bibliography at the end. THE PLATINUM METALS CHAPTER I PLATINUM METALS: THEIR OCCURRENCES, CHARACTERS AND USES INTRODUCTION THE metals which comprise the Platinum group are the follow- ing : Platinum, Palladium, Iridium, Osmium, Ruthenium and Rhodium. Up to the year 1914 Russia produced over 90 per cent, of the world's supply of platinum, the Republic of Colombia, South America, ranking next in importance with about 5 per cent. Owing, however, to the war and to the chaotic condi- tions brought about by the revolution, the output of Russia has considerably decreased, and although the Colombian pro- duction has been steadily increasing, the increased demand in connection with munition manufacture caused a somewhat serious shortage during the latter stages of the war, which was especially felt in the United States. As a result much ex- ploratory work has recently been carried on in an endeavour to discover new deposits of importance ; but up to the present, although several fresh occurrences have been brought to light, results have on the whole been disappointing. OCCURRENCES Platinum usually occurs in nature as native metal alloyed with one or more of its allied metals in the form of very fine grains more or less flattened ; sometimes in the form of irregu- lar nuggets ; and occasionally, though rarely, in small cubic crystals. It is sometimes coated with a black layer of iron .2 PLATINUM METALS oxide, which may be magnetic, in which case it is not easily recognizably. When unrefined it is referred to as "crude" platinum. With the exception of a certain amount of the platinum metals, obtained from the refining of copper and gold bullion, particularly from the copper-nickel deposits of Sudbury, Ontario, about 99 per cent, of the whole supply is derived from alluvial deposits. Several occurrences of platinum in situ are known, but so far few are of commercial importance : however, in view of the indications of exhaustion shown by some of the placer deposits, notably in Russia, the exploration of primary ores is now receiving more attention and practical results have already been achieved in Russia and in Spain. The mother rocks from which the deposits are derived, in the large majority of known cases, consist of basic and ultra- basic igneous rocks, including peridotites, pyroxenites and dunites. The two first are composed of iron magnesian sili- cates, pyroxene, augite and hornblende with olivine, chromite, ilmenite and magnetite : the dunites consist principally of olivine with some chromite. These rocks are often found to have undergone more or less alteration to serpentine. In addition, platinum has been found in quartz veins, notably at the Boss Mine, Nevada, and in a few known cases it has been derived from formations in schistose, or altered sedimentary rocks. When present in serpentine, platinum is usually disseminated through the rock in fine particles. It seldom occurs in a lode formation. In sedimentary rocks it usually occurs in sand- stones. In cases where alluvial deposits have been derived from the basic igneous rocks, the associated minerals are usually chromite, magnetite, ilmenite, iridium and osmiridium. In sedimentary deposits the metal is commonly associated with quartz, copper, nickel, silver and palladium. Platinum has been found in certain varieties of the copper ores tetrahedrite and bournonite. It has occasionally been located in shales and in coal, although not in recoverable quantities. In the latter case, in an Australian coal, it is associated with vanadium [i/p. 992]. Several cases are known of platinum being present in meteor- OCCURRENCES 3 ites, two well-authenticated instances having been reported from Mexico. Platinum has been shown to exist in meteoric iron from New South Wales. Crude platinum, as recovered, contains from 70 to 90 per cent, of the metal, and, as mentioned above, is really an alloy of platinum with one or more of the allied metals, the chief impurities consisting principally of iron and copper. The table on the next page gives the analyses of typical samples of crude platinum from the Urals, California, British Columbia, and other places. Platinum also occurs in combination with arsenic in the mineral Sperrylite (PtAs 3 ), in the form of minute octahedral crystals. The colour of this mineral is tin white, its lustre is metallic and brilliant, its hardness varies from 6 to 7, and its specific gravity is 10-6. The mineral is brittle and breaks with a conchoidal fracture. It is very rare, and is in- teresting as being the only mineral of platinum known besides the native metal, f It occurs associated with sulphide minerals of magmatic origin in gabbros and diabases, notably in the nickeliferous pyrites of Sudbury, Canada, and in the copper ores of the Rambler Mine, Laramie, Wyoming. It is probable that the palladium, which is also found in these deposits, is similarly present in the form of an arsenide, but such a mineral has not yet been definitely proved to exist. The following is an analysis of a sample of Sperrylite : platinum, 54-47 per cent. ; rhodium, 0-76 per cent. ; palladium, trace ; arsenic, 42-23 per cent. ; antimony, 0-54 per cent. [3/P- 69]. PROPERTIES OF THE PLATINUM METALS Platinum. The colour is white with a greyish tinge. When pure it is very malleable and ductile. Its coefficient of ex- pansion is less than that of all other metals. Platinum fuses at about 1750 C., but the presence of impurities lowers the melting-point. Its specific gravity is 21-5, and its hardness is from 4 to 5. Its electric conductivity is low, being 13-4 atoC. [ 4 /p. 398]. Platinum is not acted upon by either nitric, sulphuric or PLATINUM METALS 1111! * o - ) p O rfO "> 53 3 3* 3? O O l^O OO N f^ O , O >O O O O N iO CO O Ov 'Jt'OO I vO t^OO I M O^ CO CO p O 111 6 6 H en I V cVi 6 M ^*" f* <>vo Q ' ' ' v W ^t" 1 1 co ir> O vO O O\ vS op ^ ^t- O O t^c co co co tS rj- ^f CO CO *o w t^. vo oo M *o o o o o ^t- -*-O co f 9^ *P M ur>co coob < ,^^^i I 2R3.$8#S&| Jj N M 6 M ' MMCOMOOHIM M o o * tf>vO vp 9 M M M CO OO* CO CO*?* M COOO N O ^)^ vS O* w IH Op I O M cooo oo ^- N t^ t--oo o M M O ^- O COVO 00 C-OQ CO t^ Tt- CO M in M rt- rh 6 ^- C> M (M M MOO N ipcOv>p\OvO M TfN CO ipop TfOO rf M v> coMobvo is Nobobvo ^t-ir>6\M OMv6 t>. c*oo t^.oo oo t>.vo c>.co oo oo o?i i 8 ? o o I ' co o 00 if JpJ !^ * ' 'W o5 rj ^ O^ O fO CO fv H * *<* O &O u~> 10 o . o o o . -f- ON OO N ' 0" CO iO M M o O^ >O O M N iO MO , oo do t>> . *- . . >O OO O\ M N O >OOO ^ *" ' s^l 4- !> O * N O CO O "tf-oo t> H- 1 *. 1 N M "^ 1 M IO . CO 00 OO O N O CO t* M O rf COOO N J? 1 !o M i S?, 2%S N I O_ I \O O l> | M M H O CO OOO CO "f ^ o t>* o >0 o M 00 O ON CO 10 |I> U"> -^- - t^. ON Tf t^ * PI O CO <* ON co vo 00 CO vS S 1 o o pf 00* oo" CO T*- . en 22 i 1 a . $ a %% # 8 N a 2.^> d g'^'rt'^ rt 'lliy||o| 3 3 V K 44 H o i8 PLATINUM AND ALLIED METALS bian outputs were sold to England during the war, as well as most of the Australian and Indian production. Much of this metal was refined in the United States. According to J. E. Orchard [17], the commercial control (financial) of the world's output of platinum of 267,233 oz. of 1913 was divided as follows : France, 74 per cent. ; Russia, 18 per cent. ; United States, 4 per cent. ; British Empire, 2 per cent. ; other countries, 2 per cent. ; whilst the political control (territorial) was divided as follows : Russia, 93 per cent. ; Colombia, 6 per cent. ; other countries, i per cent. ASIA INDIA Traces of platinum and iridium have been noticed in asso- ciation with the gold obtained from native workings at Bonai City. The gold occurs in a deposit of iron oxide, which forms the cementing material in a hard stratum of quartz pebbles. The oxide is separated by pounding, and then washed away to extract the gold. The proportion of platinum to gold is probably less than i to 20. Platinum occurs, associated with gold, in the gravels of the Irawaddy River in Burma. A small quantity of platinum is obtained at Myitkyina by the Burma Gold Dredging Company. During the years 1911-13, 152 oz. were won by this company. In 1915 the output was 17-7 oz., and in 1916, 9-25 oz. In 1917, 4 oz. only were produced [18]. Owing to the cessation of the gold-dredging operations at Myitkyina, Burma has ceased to produce platinum, the quantity recovered during the year 1918 being only 0-31 oz. [90]. It has also been located with iridosmine in the auriferous gravels of the rivers draining the slopes of the Patkoi Ranges, both on the Assam and Burma sides [19]. AFRICA RHODESIA Platinum has recently been located in the Gwelo district, about 6 miles north-east of Indiva siding, where it occurs in the great dyke of norite, which is here about 4 miles RHODESIA 19 wide. A. E. V. Zealley, the late assistant Government geologist, made this occurrence the subject of a special report [20]. The country rock is a serpentinized dunite. The deposit is capped by a ferruginous siliceous gossan from 4 to 5 ft. wide, which may be traced on the surface for about 100 ft., and is comparable to a fissure vein. The gossan consists largely of haematite and chalcedony, with occasional veinlets of copper and nickel minerals. Although the presence of platinum in the ore could not be detected by panning, the possibility of its occurrence on geological grounds was considered, and a sample of concentrate from an unstated amount of ore was forwarded to the Imperial Institute for analysis. The sample was found to contain platinum to the amount of i dwt. 20 gr. per ton. A report on the further development of this deposit is awaited with interest. A sample of concentrate from an unstated amount of material from the gem-bearing gravels of Somabula Forest, Gwelo dis- trict, was received at the Imperial Institute from the Director of the Geological Survey of Southern Rhodesia in November, 1918. On analysis this sample yielded the following per ton : platinum, 3 oz. 12 dwt. ; osmiridium, 7 oz. The concentrate also contained a large proportion of gold. As shown by the latest information available, the deposits, although undoubtedly rich, appear to extend over a limited area. According to an analysis made at the Imperial Institute, a sample of chromite from Southern Rhodesia (Selukwe) contained 0-17 per cent, copper and nickel oxides, and a trace of platinum [21], H. B. Maufe [22] has stated that as the River Umtebekwe drains two areas of ultra-basic rock containing chromite, it might be expected to contain alluvial platinum, as well as gold, and, as a matter of fact, platinum has actually been discovered in a reef in the Great Dyke (norite), at the head of the Umtebekwe valley. The presence of platinum was recently reported art Wil- loughby's Halt, 12 miles south of Gwelo. UNION OF SOUTH AFRICA Cape Colony [23]. Platinum is present in varying quantities in the copper-nickel deposits at Insizwa, situated in the Cape 20 PLATINUM AND ALLIED METALS Province, close to the boundary between East Griqualand and Pondoland. The rock formation consists of a basin-shaped mass of intru- sive norite, averaging from 2,000 to 3,000 ft. in thickness, and lying in the shales and sandstones of the Beaufort Series of the Karroo System. The ore body consists of sulphides of copper and nickel, in association with pyrrhotite, the minerals occurring dissemi- nated near the basal margin of the intrusive in olivine picrite. Gold and silver are also present in small quantities. The average copper and nickel contents in the ore are each about 4 per cent., and the platinum content averages from 2 to 3 dwt. per ton, the platinum being unequally distributed through the ore [24/p. 14]. It is not certain in what form the platinum occurs. It does not appear to be present as sperrylite. In the opinion of W. H. Goodchild it may occur in close association with the silver [24/p. 35]. Mining operations have been intermittently carried on here during the last fifty years, the last exploratory work coming to an end in 1911. Operations were, however, resumed early in 1920. Transvaal. Small amounts of platinum and its allied metals have from time to time been noticed in black sands from the battery "clean-ups" on the Rand at Klerksdorp and other gold-mining districts, and platinum to the amount of 2\ dwt. per ton is reported to have been present in residual slimes at the Rietfontein mines [25]. A specimen, consisting of about 85 per cent, osmiridium and 15 per cent, platinum, recently received at the Imperial Institute, was stated to have been taken from a compact shale, immediately underlying the banket reef in one of the mines of the Klerksdorp district. In the large majority of the gold mines, however, the platinum metals, if present, appear to exist in such small quantities as to escape detection. A series of samples of chromite from Kromdaal, near Rusten- burg, showed from a mere trace to i dwt. of platinum per ton, and one sample of chromite from the Secocoeniland deposits showed as much as ij dwt. of platinum per ton [26]. CANADA 21 NORTH AMERICA CANADA The occurrence of platinum in Canada was first observed in 1862, in the course of gold-mining operations on the Rivire-du- Loup and the Riviere-des-Plantes in the province of Quebec [27/p. 210]. Since that time platinum has been found in a number of localities associated with auriferous gravels, but the crude metal has only been obtained commercially from the Simil- kameen district in British Columbia. These deposits first attracted attention in 1885. All the workings are alluvial, although the platinum has in several cases been traced to its parent source. Alberta. Platinum and gold in minute grains, closely intermixed, are found in the North Saskatchewan River, near Edmonton. In 1918 certain platinum occurrences were examined by the Munitions Resources Commission, visits being paid to Fort Saskatchewan and the Peace River district, in Alberta. These deposits, however, proved to be disappoint- ing. In the former locality, which was carefully tested by drilling, the values of the samples obtained averaged less than 10 cents in gold and platinum per c. yd. of gravel [28/p. 427]. British Columbia. Platinum, associated with gold, which is the dominant metal, occurs in the Tulameen River and its tributaries, the principal of which is Slate Creek, others being Cedar, Eagle, Bear and Granite Creeks. The metal is present in small rounded grains, or pellets. Chromite is often found intergrown with the platinum, olivine and pyroxene usually occurring in association. The heavy minerals remaining with platinum in the concentrate are titaniferous magnetite, chromite and native copper. The platinum is sometimes magnetic, probably due to the covering of the grains by small particles of magnetite [29]. The following analysis, according to G. C. Hoffmann, is representative of an average sample of crude platinum from the Tulameen River: 22 PLATINUM AND ALLIED METALS Per cent. Per cent. Platinum . . . 72-07 Osmiridium . . . 10-51 Palladium . . . 0-19 Copper . . . 3-39 Rhodium . . . 2-57 Iron .... 8-59 Iridium . . .1-14 Gangue (Chromite) . 1-69 Owing to the presence of osmiridium in considerable pro- portion, 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 Olivene 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 [27/p. 210]. American capital dominates the platinum industry in the district. In 1918, at the request of the Imperial Munitions Board, special in- vestigations 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 [a8/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, CANADA 23 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 [30]. 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 [30]. 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 Clear- water 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 [31]. At Si wash 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, con- tains, besides gold and silver, platinum, palladium and osmiri- dium, 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 [32]. 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 pre- ceding 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 [33]. Analyses of the samples from different auri- ferous reefs were made by the Department of Mines in 1917, and yielded platinum varying in amount from a trace to o-i 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. 3 24 PLATINUM AND ALLIED METALS 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 [34]. 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 forma- tion of the gold-bearing series of the Atlantic coast. The platiniferous mineral is supposed to be sperrylite, with which is associated arsenopyrite. Ontario. Sudbury is one of the few places where platinum is profitably extracted from deposits in situ. The metal, which was first discovered in this region in 1889, is found mostly in combination with arsenic, as sperrylite associated mainly with chalcopyrite in the well-known copper and nickel-bearing deposits of the district. The origin of the ore- bodies has not yet been settled. They are either marginal deposits in, or off- shoot deposits to, a norite laccolith, which has intruded sedimentary rocks, the ores consisting principally of chalcopyrite, pyrrhotite, and pent- landite. Metallic platinum, gold, silver and palladium occur in the ore, the last also, probably, as an arsenide. The highest platinum content is associated with the highest copper con- tent ; the highest palladium with the highest nickel. Accord- ing to Roberts and Longyear [35] the mean analysis of rocks of from sixteen drill holes gave an average ore content of : copper, i'ii per cent. ; nickel, 1-95 per cent. ; silver, 0-223 oz. ; gold, 0-022 oz. ; and metallic platinum, 0-0068 oz. per ton. The ore is principally worked for its nickel and copper content, and yields a large proportion of the world's supply of nickel. The ore is first smelted at the mines, and a portion of the low- grade matte so produced is then shipped to South Wales for final treatment, the remainder being sent to the recently- constructed refinery of the International Nickel Co., at Port CANADA 25 Colborne, Ontario, and to the United States. It was stated in 1903 that this matte contained on the average 1-25 oz. of the platinum metals per ton of nickel content of the matte, of which about 80 per cent, was extracted [36/p. 10]. The Victoria Mine, owned by the Mond Nickel Co., is stated to carry a high percentage of the precious metals, as is also the Vermilion Mine, although in the latter case the ore body is very small. In 1917 the total output of copper-nickel ore from these deposits amounted to 1,506,828 tons, of which the Canadian Copper Co. raised 1,139,629 tons, the Mond Nickel Co. 361,335 tons, and the Alexo Mining Co. 5,864 tons. The nickel content of the ore of the Canadian Copper Co. was about 2-5 times that of the copper, whilst the ore mined by the other two companies contained the two metals in approximately equal proportions. The matte produced by the Alexo Mining Co. is smelted by the Mond Nickel Co. According to the report of the Royal Ontario Nickel Commis- sion, the matte produced by the Canadian Copper Co. in 1916 was estimated to contain 4,640 oz. platinum and 8,460 oz. palladium, corresponding to o-io oz. platinum and 0-15 oz. palladium per ton of matte, the International Nickel Co. recovering in that year 1,093 oz. platinum and 257 oz. allied metals. This company is now reported to have improved its methods of recovery. In 1918 the total matte shipment by the Canadian Copper Co. is stated to have contained, among other precious metals, 8,677 oz. platinum and 13,016 oz. palladium [37]. According to information supplied by the Mond Nickel Co., their nickel residues derived from the refining of the matte are taken over by Johnson, Matthey & Co., Ltd. During the years 1915-18 the residues disposed of were estimated to con- tain the following amounts of platinum metals : (In oz. troy.) 1915. 1916. 1917. 1918. Platinum ..... 3,078 3,782 4,913 4,465 Palladium ..... 5,474 Iridium and Rhodium 973 - - ' ~ 26 PLATINUM AND ALLIED METALS Messrs. Johnson, Matthey & Co., Ltd., have kindly supplied the following figures of platinum-extraction from these residues : Oz. troy. 1916 ..... 3,722 1918 ..... 4,958 The British America Nickel Corporation, who are developing some large deposits in the same district, are also erecting a re- finery near Hull on the Ottawa River. It is stated that they will employ the Hybinette process of electrolytic refining, and expect to obtain a high recovery of the precious metals [28/p. 425]. With gradual improvements in the refining process, and with the refining of the whole of the matte produced, instead of a portion only, as at present, it seems probable that the production of platinum metals by the three nickel companies may in time exceed 10,000 oz. per annum. The 1919 report of the Ontario Bureau of Mines shows that in 1918 the International Nickel Co. treated 62,250 tons of matte for 650 fine oz. of platinum, 787 oz. of palladium, and 473 oz. of metals of the rhodium group. This cannot be used as a basis of calculation, as the proportions are not constant. On the Quinn claims, near the Croesus Mine, Munro Town- ship, is auriferous quartz containing platinum. Five assays gave a platinum content of value ranging from $180 to $1,800 per ton (with platinum at from $40 to $50 per oz.) [30]. The Abro Mine in the Timiskaming district in 1915 shipped between 5,000 and 6,000 tons of ore, containing 0-03 oz. of palladium and platinum per ton. The ore consists of pyrrhotite, chal- copyrite and pentlandite, in a gangue of altered peridotite and serpentine [7]. Yukon Territory. Platinum occurs associated with gold in small quantities in most of the tributaries of the Yukon River, notably at the mouth of the Hootalinqua River, and in the River Lewis [36/p. 12]. NEWFOUNDLAND Chromite derived from the serpentinized area in the region of Mount Cormack, situated in the central part of the island, has been found to contain small quantities of platinum [38]. AUSTRALIA 27 AUSTRALASIA AUSTRALIA The most important occurrences of platinum in the Common- wealth are at Fifield and at Platina, in New South Wales. The outputs of crude platinum in Australia in recent years were all exported to the United Kingdom as under : Year. Troy oz. Year. Troy oz. 1910 332 1915 . 56 IQII 470 1916 . 82 1912 610 1917 259 1913 442 1918 . 607 1914 244 Note. These figures do not include the osmiridium produced in Tasmania. Recent imports of manufactured platinum were as under : Oz. Oz. 1910 320 1914-15 - 223 I9II 504 1915-16 89 1912 318 1917-18 18 1913 301 The question of the refining of platinum in Australia has been under consideration for some time ; so far the crude material has all been sent to England. The outlook for future production of crude platinum in Australia is not promising, with the exception of that of Bald Hill district, Tasmania. New South Wales. Platinum is obtained at Platina, in the Fifield division, in the east central part of the State, from a buried gravel channel, in which it occurs in association with gold and osmiridium. The rocks in the vicinity of the " leads " consist chiefly of slates, but the source of the platinum is not known [2/p. 557]. These deposits were first exploited in 1894, and from that year to 1918 inclusive, the total output of platinum from New South Wales was 14,680 oz. [39]. The gravels have yielded amounts of 6 dwt. platinum and 2 dwt. 28 PLATINUM AND ALLIED METALS gold per ton, but according to Government reports the richer deposits are nearly worked out ; mining operations are carried on with great difficulty, as there is a great scarcity of water and a deep overburden, varying from 20 to 80 ft. in depth. It is estimated that there are 200 acres of platinum-country available, sufficiently rich to pay, were it worked on a large scale with an abundant supply of water [40]. A new occurrence has recently been discovered about i mile distant from the old Platina deep " lead," the platinum being associated with small quantities of gold. The " lead " has so far been proved to extend over an area about i mile in length, and from 60 to 150 ft. in width, the wash varying in depth from a few feet to up to about 80 ft. The pay gravels, which rest on shales and sandstones of Silurian and Devonian age, intruded by dioritic dykes, are stated to be from i to 3 ft. thick. The following analysis is representative of the crude platinum produced : Per cent. Per cent. Platinum . . . 75-90 Osmiridium . . . 9-30 Iridium . . . 1-30 Iron . . . . IO-I5 Rhodium . . . 1-30 Silica .... 1-12 Palladium . . . trace . 14.] Platinum is frequently found in beach sand deposits on the coastal border between Queensland and New South Wales, notably at Ballina, close to the mouth of the Richmond River ; at Evans Head, further south ; and at Currumbin, near the mouth of the Tweed River. In this locality black sands con- taining platinum, associated with gold, cassiterite, monazite and osmiridium, accumulate on the beaches during stormy weather. At Ballina and Evans Head, the platinum pre- dominates over the gold, but at Currumbin, further south, the gold is in the greater quantity [2/p. 557]. The minerals are present in a very finely divided state, and separation of the valuable metals is a matter of considerable difficulty. The problem does not appear to have been satisfactorily solved up to the present time, although promising experiments have recently been carried out with screening and magnetic treat- ment. The deposits are, unfortunately, very low grade, AUSTRALIA 29 The sources of the metals are uncertain. The platinum and osmiridium appear to have been derived from the western edge of the Clarence coal measures, which now exist only as fragmentary outcrops. The gold, tin and monazite may have their origin in granite and other rocks of the New England tableland. Chromite is present in some of the Currumbin sands, which suggests serpentine as the probable source of platinum [2/p. 557]. Other associations are zircon, garnet, tourmaline, ilmenite, magnetite and sapphire. In the Broken Hill district, principally at Little Darling and Mulga Springs Creek, platinum has been proved to extend over a considerable area in a copper-nickel gossan, closely associated with gabbro, decomposed gneisses and schists. In addition to platinum, the amounts of which vary from a trace to 16 dwt. per ton, gold, silver, iridium and palladium are also present [42]. The deposits bear some resemblance to the nickel deposits of Sudbury, Ontario, and it is thought that here, too, the platinum occurs combined with arsenic, as sperrylite. Queensland. In addition to the beach deposits between Southport and Currumbin, described above, platinum has been found in Coopooroo and Wairamba Creeks on the Russell Goldfield, near Innisfail ; also in the Lucknow and Alma " reefs " of the Gympie Goldfield, where it is present in quartz lodes with native gold, and arsenopyrite, the accompanying rocks consisting of slates, alternating with volcanic tuffs and conglomerates ; the metal also exists in the neighbouring gold-bearing alluvial deposits of Brickfield Gully. Another occurrence of alluvial platinum is known at the head of the Don River in Central Queensland [2/p. 556]. Victoria. Platinum occurs in the Walhalla Copper Mine, where it is associated in a hornblende-diorite lode-formation with copper pyrites, gold and silver. The ore is stated to con- tain from 2 to 7 dwt. platinum per ton. In the Thompson River Copper Mine platinum is found in a hornblendic rock rich in chalcopyrite. Tasmania. Iridosmine has been produced from the Bald Hill district near Waratah, in the north-western part of the state, since 1900, the metal being obtained from placer deposits in Nineteen Mile Creek and its tributaries, Linger-and-Die, PLATINUM AND ALLIED METALS McGinty's and Barren Creeks, and from Savage River. It has been located in situ in the rocks of Bald Hill, principally in serpentine, but also with chalcedony and opaline silica in lode-formations. In the former case, it is associated with magnetite, pyrite, pyrrhotite, nickel and gold. The iridosmine in the placer deposits is sometimes coated with iron oxide, and is also at times found enclosed in chromite. The following analysis in percentages, made at the Imperial Institute, is typical : osmium, 57-09 ; iridium, 33-80 ; platinum, 0-37 ; ruthenium, 8-19 ; palladium, 0-21 ; gold, 0*04 ; iron, 0-30 ; copper, trace. Other localities in Tasmania at which osmiridium has been located are Heazlewood River, Whyte River, Castray River, Huskisson River, Wilson River and Boyes River ; also the Badger gold diggings, west of Savage River, and the Salisbury goldfield near Beaconsfield. The following table gives the recent annual output of osmi- ridium in Tasmania : Year. oz. (troy). Value in . Year. oz. (troy). Value in . 1910 120 530 1915 247 I,58l 1911 272-9 1,188 1916 222-2 1,899 1912 778-8 5>742 1917 332-1 4,898 1913 1,261-6 12,016 1918 1,607 1914 1,018-8 10,076 1919 1,669-7 39,6l4 South Australia. In the north-east part of the State traces of platinum have been recognized by analysis as occurring in the outcrop of a lode near Boolcoomatta. Further informa- tion on this occurrence is not available. Papua. Osmiridium, associated with small amounts of gold only, is known to occur as alluvial in the neighbourhoods of various serpentine areas ; in the Lakekamu district, in flaky form ; in the Yodda Valley, in appearance similar to native bismuth ; and in other places in shot-like granules [88]. NEW ZEALAND Platinum is only obtained commercially in New Zealand from the Orepuki district of Southland, where it is produced NEW ZEALAND 31 by the Round Hill Gold Mining Company as a by-product in the washing of auriferous gravels. According to information recently supplied by the Mines Department, the annual out- put of crude platinum for the last ten years has averaged 30 oz., but in view of the recent falling-off of the gold production in this locality, the prospects of any increase in the output of platinum seem small. In South Island the presence of platinum has been reported on the Thames River in quartz lodes, in a region of serpentine and diorite, and in a pyritic lode near the Taramakau River in the district of Westland, in close proximity to sheets of altered magnesian eruptive rocks [2/p. 557]. The platinum in the latter case occurs in association with silver, in the proportions of about 7 parts of the latter to i of the former, together with pyrite and limonite. Samples taken from the lode have been stated to have an average content of 3 dwt. 8 gr. platinum per ton [43]. Other localities in South Island where platinum has been located are the Taraka and George Rivers, which flow into Awarua Bay ; the east coast of Otago, in beach sands and river gravels ; the Clutha River ; and the Nelson gold district. Concentrates containing up to 2-5 per oz. per ton are re- ported to have been obtained from the Parapara sub-division. Platinum in New Zealand is often associated with gold, and the deposits are in many cases similar to those of the Urals. 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 [30]. 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 exten- sive 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 ; FRANCE 33 From Year. United Kingdom. Russia. Germany. Serbia. Switzer- land. Austria- Hungary. Other countries. Total. 1910 480 5,878 1,104 204 85 . 44 7.795 I9II 575 6,895 822 782 I2 7 192 9,393 1912 5,454 283 144 271 84 6,235 1913 78 4,500 220 2 171 97 5,067 1914 63 2,595 161 IO2 2,921 {i 88 No details avail able 578 578 41 GERMANY Platinum has recently been discovered in Westphalia, de- posits 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 re- cemented fragments which are presumably derived from the basal granite formation, underlying the platinum series [44/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-desseminated state, is associ- ated 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. (i oz. troy) platinum per ton [45]. 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 [3]. As mentioned above, about 25 per cent, of the Russian output of platinum before the war was refined in Germany, 34 PLATINUM METALS and it is known that German capital was helping to finance the pre-war platinum operations of that country [3]. 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 Year. United Kingdom. France. Austria- Hungary. Russia. United States. Other countries. Total. IQIO 419 846 265 2 7 8 I2 7 216 2,151 IQII 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 con- sisted 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 i6s. lod. per oz. ; but owing to the sub- sequent rise in value of platinum, the coinage was discontinued in 1845 [46/p. 606]. The platinum industry began to develop in 1869, the price at that time being under 5 per Ib. [47], but from that year onwards the value, although subject to considerable fluctua- tions, has steadily increased. It has been estimated that since the beginning of the industry in Russia, about 6,000,000 RUSSIA 35 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 I9II 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 Verk- hotur Perm North Verk hotur Tcherdynsk South Ekater- inburg 111,070 46,068 11,862 6,359 972 121,314 46,885 11,362 5,016 1,040 118,048 38,709 13,166 6,162 1,382 102,552 36,878 n,376 6,109 816 106,528 38,050 7.426 4.753 421 80,985 22,996 12,288 3.5i8 2 52,353 I4,8l8 9,968 1,542 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 follow [i-5/p. 923] : To. 1911. 1912. 1913- 1914. 1915- Great Britain . France Germany . United States . 1,053 168,527 51,612 2,107 169,580 50,558 1,580 140,615 58,458 64.778 17,906 66,884 7,900 5.266 Total . 221,192 222,245 200,653 82,684 80,050 36 PLATINUM METALS 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 Societe Anonyme de 1' 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 Societe Anonyme de T 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 [i5/p. 923]. In February 1917 the Government further enacted an order prohibiting the im- portation 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 IDS. 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 [48/p. 17]. According to N. Vissotzki [49], the platiniferous belt of the Urals, geologically speaking, consists of four parallel bands striking, roughly, north and south ; the westernmost RUSSIA 37 of these, made up of crystalline schists, forms the watershed between Europe and Asia. The next band to the east com- prises 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 Car- boniferous 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 : (i) The Shuvaloff Estates, Isov district, on the River Iss, near Goroblagodat. (2) The Demidoff Estates, Nizhni-Tagilsk district, on the Mart j an 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 38 PLATINUM METALS it is obtained from the Sosnovki, Kytlymi, and Mala Kosva Rivers ; further north again, platinum occurs with ff 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 [i5/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 as- sociated 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 di- mensions 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 [5o/p. 299]. Platinum nuggets are rarely found, but three of large size were discovered in the Nizhni-Tagilsk district, their weights respectively being 25j lb., 21 lb., and nj Ib. Duparc, in a brief description of the geology of the deposits, states that they are essentially of magmatic origin. The RUSSIA 39 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 esti- mated 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 [51]. The amount of the platinum in the wash is very variable. The average yield was formerly over J 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 [52]. 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 pro- ductive area is about 170 sq. miles, and from 15,000 to 20,000 miners were employed before the war [2/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 4 4 o PLATINUM METALS modern >j\ 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 bed-rock. 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 [53]. 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 be- come 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 ii J 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 [54]. An experimental test, carried out in March 1917, is stated to have produced over 200 oz. platinum from 9,720 Ib. chromite slack. Another experiment with 3,600 Ib. of grey slack, "or fines," consisting chiefly of undecomposed dunite obtained from the dredges, is reported to have yielded J oz. of platinum. RUSSIA 41 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 [2 /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 quan- tities. [2/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 [55], 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 42 PLATINUM METALS [lo/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, ac- companied by magnetite, ilmenite, zircon and, frequently, gold [56]. ASIA ARMENIA Platinum, in association with gold, is reported to occur in the district of Batum and Sasun, on the Charokh River [44/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 [57]. The deposits occur in streams, which rise in the Bobaris Mountains, where the country rocks are composed of schists and gneisses, in- truded by serpentine gabbro and diorite dykes [5o/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 in- timately 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 P er cent - [58]. The rare mineral laurite, a sulphide of ruthenium and osmium, was discovered in these deposits. According to L. Hundeshagen [59], the platinum occurring in the diamond placers of western and south-eastern Borneo CHINA JAPAN SUMATRA 43 is in the form of thin scales, ranging from o-i to i-o 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 indium 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 develop- ment 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 occur- rence is stated to bear some resemblance to that of the plat- iniferous 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 [60]. 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 [g/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 [59] is of opinion that the present ore de- posit was originally a layer, or a big lens, of limestone imbedded 44 PLATINUM METALS 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 o-i 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 [61], UNITED STATES 45 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 latent es. The metal exists in a very finely disseminated state, invisible to the naked eye [62]. 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 wito the United, States (In troy oz.) 1913. 1913. 1914. 1915. 1916. 1917. 1918. From British countries t Canada . United Kingdom Other British countries 777 19,169 4 582 16,595 55 6,476 139 7,692 5" 9,513 5 332 3,195 53 357 25 Total, British countries 19,950 17,177 6.531 7,831 9,569 3,527 635 From foreign countries : France . Germany Netherlands Norway . Russia (European) Colombia Other foreign countries 25.723 24,673 24,519 29,075 16,570 30,015 258 815 3,48o 2,350 480 63 3,395 10 159 512 2,507 120 207 57 814 1,665 3 Total, foreign countries 48,396 53,594 47,658 6,373 4,076 2,891 2,4182 Grand total, oz. 68,346 70,771 54,i89 14,204 13,645 6,418 3,"7 [64] 4 6 PLATINUM METALS o .s i .8 vO CO J ^ O N t^ CO *O CO s o M o _( M j | to covq^ >o t^* U M IO M ^ co" Tt ' < IOM vO N M COO M Ov CO tM vO 00 IO w O vO t*^ O^ o M o I >0 M t^ O M o\ M ^ co M CO O O s Tf- N W 00 00 CO M 1 O O> M I 00 O M M *M (> q | co M 1 .OM ^ O ON vo" vo" CO V> cR O" CO CO w W to ^ CO O ? O vO 00 O 1 1 N > to W MOO o^ >O CO N M J 1 M CO CO ON M vO" VO CO ci co M M vo" 4* ON COCO 1 10 o 1 M vO M 10 N O !> N O "4-vO i i 00 i q; M^ rf M 1 1 co 1 M v? M M *2 2 CO CO i 1 CO M rfoo M VO 1 CO CO | oo rt-too M oo Tt- o i i i vo i to M | 1 | t 1 1 -a i 2* oo" oo" J^ co O M" T^- M -*-> o ^_^ M Tj- a *** to 8 OO >O O> I s * to l> CO , . * M CO t^ o d *KJ O M I oo" 1 oo" vO rf O M $SI 1 1 IS M >O CO 1 (S f CO CO s * en 1 tn en 02 .2 * j 6 n. 55 O 1 1 | 5 kOcn 5 Eib * 2 .S O N ^ W S ^1 S3 .*&> . - ^ .1 O -4-> 111 J s Illl||l's| 1 o gOOO 1 g c5^i^ocSo 3 d 1 fi: A UNITED STATES 47 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. indium and 48-56 oz. of rhodium, a total of 85-725 per cent, of platinum metals, slightly above the usual 83 per cent. [63]. 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 [65]. 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 i. The concentrates produced, representing about 3^ 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 [89]. 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, i 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 [ 4 8/p. 19]. A possible source of platinum appears to lie in the neigh- bourhood of the Red Mountain, on the Kenai Peninsula. The mountain is composed of fine-grained dunite, in which abun- 48 PLATINUM METALS dant chromite occurs. Up to 1917 no placer mining had been attempted in this locality [66]. 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 chalco- pyrite ; 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 i oz. of palladium to every 8 to 12 per cent, (units) of copper [67]. 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 [68]. California and Oregon. Platinum has been proved to exist over a wide area in plaoer 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 [5/P- 3]- 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 [48/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 UNITED STATES 49 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 [48/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 [lo/p. 540]. Some alluvial platinum has been recovered at the Bean Hill Gold Mine, situated 12 miles south-east of Placer ville, and this locality is at present under investigation [69]. Calif ornian metal contains from 25 to 45 per cent, indium. 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 [48/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 [io/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. fo/p. 592]. 50 PLATINUM METALS 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 [70]. 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, in- truded 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 [71]. In 1919 the Boss Mine shipped $22,365 worth of platinum- bearing ore [72]. 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 i-o oz. of platinum and palladium, 075 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 pre- cipitated 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 pre- cipitated 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 [73]. Metals of the platinum group have recently been shown to exist in small quantities in the ore of the Oro Amigo Mine, UNITED STATES 51 situated between i 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 o-i 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 [lo/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 [io/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 i, 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 [74]. It is stated that the platinum and palladium contents vary directly with the percentage of copper present, a typical assay giving the fol- lowing values : copper, 5 per cent. ; gold, 0-02 oz. .; silver, I oz. ; palladium, 0-4 oz. ; and platinum, 0-6 oz. per ton [75]. Utah. Platinum and gold in very fine particles occur in the Green River, east of Vernal ; also in the Colorado River, near Kite, 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 [4i/p. n]. 52 PLATINUM METALS SOUTH AMERICA BRAZIL Jose Vieira do Couto, in 1801, first pointed out that platinum occurs in the sands of the Lages River, near Conceicao, Minas Geraes. According to E. Hussak [76], platinum in that region occurs only in the alluvium of rivers having their rise on the eastern slope of the Serra do Espinhaco. 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, mammil- lated 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 quart zite, or from the over- lying conglomeratic quart zite. 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 5 iron, o-io ( = 96-86), undetermined (rhodium and osmium), 3-14. In the Rio Abaete, Minas Geraes, platinum very different in appearance and chemical composition from that of the Serra do Espinhago occurs in placer deposits, associated with gold, diamonds and the following minerals : rolled pieces of a BRAZIL 53 hydro-phosphate of barium and aluminium (gorceixite = " marumbe " of miners), garnet, almandite, pyrope, ashy-blue oxide of titanium (bagageira regarded as a good indicator for diamonds), magnetite, chromite and calcium- titanate (perov- skite). Pyroxene-olivine rock, a typical picrite-porphyry, rich in perovskite, and granular magnetite rocks, rich hi 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 laminae, 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 Cuyaba and Coxim rivers in the southern part of the State of Matto-Grosso, also contain some platinum. According to Luiz Castano Ferraz [77], platinum occurs in the River Coxipo-Mirim, where gold- dredging is carried on, combined with palladium, iron, osmium and iridium in small spherical grams, 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, alman- dine, 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 Ituassu, Feira de S. Anna and Serra do Assurua, and it is said to occur at Sao Bartholomeu, and in the Serras do Pitango and Macahubes [78]. Platinum also occurs in Brazil as rare disseminations in the gold-bearing jacutinga, intercalated in the itabirites (e.g. at Congo Socco Mine, long since abandoned). The jacutinga occurs as narrow bands and nuclei in the itabirites, containing 54 PLATINUM METALS 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 Congo 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 pal- ladium varied from 3-89 to 4-80, and that of platinum from 0-04 to O'I2. At Candonga, gold occurs in an eruptive rock rich in magnetite enclosed in itabirite, and is probably of contact-meta- morphic 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 Congo Socco, Candonga and Itabira do Matto Dentro. In 1870 Henwood showed that the palladic gold from Congo 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- BRAZIL 55 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 con- tinuous series of mixed crystals, and that there is no indication of chemical combinations [79]. 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 [46/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 valu- able, much of this dumped metal was recovered, notably in Quibdo, the capital of the Choco 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 Choco district : Year. Oz. (troy). Year. Oz. (troy). 1911 . . . 12,000 1915 . . 18,000 1912 . . . 12,000 1916 . . 25,000 1913 15,000 1917 . . 32,000 1914 17.500 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). Year. Oz. (troy). 1910 . . . 1,600 1915 . . . 13,121 1911 5.503 I9i6 . . . 25,588 1912 . . . 6,627 1917 21,278 1913 10,461 1918 . . . 27,030 1914 - - 12,387 5 56 PLATINUM METALS The crude platinum is estimated at 84 to 85 per cent. fine. The price in 1917 fluctuated from 16 to 20 los. 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 [80]. 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 approxi- mately 85 of gold to 15 of platinum. The area including the watersheds of the San Juan and Upper Atrato Rivers is known as the Choc6 district. T. Ospina, Director of the Colombian School of Mines [81], esti- mates that in the area are 5,000 sq. miles of gold and platinum deposits, the Mir a 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 [46/p. 620]. At No vita Vieja, in the centre of the Choco district, a bed of conglomerate 6 to 12 ft. thick has been laid bare, over an area 2 J miles long and J 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 [82]. According to Castillo, the parent rock is a typical gabbro, pyroxene predominating over the felspar [83/p. 826]. COLOMBIA 57 Platinum has been found in the Choco district in serpen- tine rock. Granite also occurs in the same district, traversed by quartz lodes containing palladium, indium, 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 [83/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 Choco, 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 [84]. 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 com- panies, 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 6d. per 58 PLATINUM METALS c. yd. for dredging, and 3^. for hydraulicing [85]. In 1917 new platiniferous deposits were discovered in the Caceres district, between the Cauca and Nechi Rivers, in the depart- ment of Antioquia. The mineralized area extends along the Caceri River, a distance of 14^ miles, the width at the north end being ij miles, and 300 ft. at the southern extremity [io/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 [86]. 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 [87]. 59 REFERENCES TO LITERATURE ON THE PLATINUM METALS [i] Lindgren, W. : " Platinum and Allied Metals," U.S. Geol. Surv., Min. Res. of U.S., 1911. [2] Dunstan, B. : Queensland Govt. Min. Journ., 1917, 18. [3] Thomas and MacAlister : The Geology of Ore Deposits, London, 1909. [4] Gowland, W : Metallurgy of Non-Ferrous Metals, London, 1918. [5] Lindgren, W. : " Platinum and Allied Metals," U.S. Geol. Surv., Min. Res. of U.S., 1910. [6] Rose, T. K. : " Electrolytic Refining of Gold," Trans. Inst. Min. and Met., 1914-15, 24, p. 45. [7] Hill, Jas. M. : " The Platinum Situation," Eng. Min. 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[67] Campbell, Donald G. : " Palladium in Alaskan Lode Deposits," Min. and Sci. Press, Oct. n, 1919. [68] Board of Trade Journ., Dec. n, 1919, 103. [69] Min. and Sci. Press, Mar. 15, 1919, p. 367. [70] Hall, F. A. : Eng. and Min. Journ., Oct. 10, 1914, p. 642. [71] Knopf, A. : Min. and Sci. Press, June 5, 1915, p. 878. [72] Chem. and Met. Eng., March 24, 1920. [73] Min. and Sci. Press, March 9, 1920. [74] Eng. and Min. Journ., May 25, 1905, p. 985. [75] Taft, H. H. : Eng. and Min. Journ., 1918, 106, No. 21, p. 900. [76] Hussak, Euginio : " O Palladio e a Platina no Brasil," Annas da Escola de Minas de Ouro Preto, 1916, No. 8, 85-188. [77] Ferraz, Luiz Caetano : Annas da Escola de Minas de Ouro Preto, 1909, No. n. [78] Carneiro, A. J. de Sousa : Riquezas Mineraes do Estado da Bahia, 1908. [79] Maclaren, J. M. : Gold : Its Geological Occurrence and Geo- graphical Distribution, London, 1908, p. 25. [80] Journ. of the Royal Society of Arts, 1908, 56, p. 884. [81] Ospina, T. : Paper read before second Pan-American Congr., Jan. 3, 1916. [82] White, R. W. : Eng. and Min. Journ., 1897, 63, p. 189. [83] Castillo, J. C. : Min. and Sci. Press, 1909, 98. [84] " Platinum-seeking in Colombia," The Times, Nov. 26, 1912. BIBLIOGRAPHY 63 [85] Mining Journ., Nov. 30, 1918, p. 700. [86] Millar and Singewald : Mineral Deposits of South America, New York, 1919, p. 405. [87] Kunz, George F. : " Platinum and Palladium in Brazil," Pan-American Bull., April 1919, p. 408. [88] Min. and Sci. Press, April 10, 1919, [89] Mertie, J. B., Jr. : " The Salt Chuck Palladium-Copper Mine," Eng. and Min. Journ. , July 3, 1920. [90] Records Geol. Surv. of India, 1919, 50, pt. 3, p. 156. 6 PRINTED BY HAZELL, WATSON AND VINBY, IJ)., 1XJNDON AND AYLESBURY, ENGLAND. THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. 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