DOCSLIB.ORG

Characteristic Optical Data for Cooperite, Braggite and Vysotskite

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Characteristic Optical Data for Cooperite, Braggite and Vysotskite Canadian Mineralogist Vol. 23, pp."149-162(1985) CHARACTERISTICOPTICAL DATA FOR COOPERITE,BRAGGITE AND VYSOTSKITE ALAN J. CRIDDLE AND CHRISTOPHER J. STANLEY Department of Mineraloglt, British Museum (Natural History), Cromwell Road, South Kensington, London, Great Britain SW7 sBD ABSTRAcT monfent que cooperiteet pyrrhotine ne seressemblent pas. Les descriptionsoriginelles de Schneiderhcihn(1929a, b) Reflectance spectra for cooperite PtS and braggite portaient non pas sur la cooperite,mais probablementsur (Pt,Pd)S from the type locality at Potgietersrus, South la braggite, encore inconnue d 1'6poque.L'erreur s'est Africa, weremeasured between 2100 and 700nm. Thesespec- aggravdequand le "spectre" de rdflectance de la pynho- tra, and qualitative descriptionsof the grains, completethe tine. extraite de concentrescens6s contenir de lia cooperite, characterization of the minerals made in 1932by Bamister fut attribud d la cooperite. & Hey. The mineral association, optical properties and reflectancespectra of cooperite,braggite and vysotskitePdS (Traduit par la R€daction) from the Minneapolis Adit area of the Stillwater complex, Montana, are also described.The data for cooperiteand Mots-clds: cooperite, braggite-vysotskite, spectrede rdflec- braggite are compared with those for the type material; the tance, 6valuationdes couleurs, caract6ristiques optiques' data for vysotskite may, in the absenceof appropriate data VHN, intervalle de composition, Potgietersrus,com- for the type material from Noril'sk, U.S.S.R., be consi- plexe de Stillwater, min6raux du groupe du platine. dered characteristic for the mineral. Electron-microprobe data are provided for all ofthe grains measuredinthe reflec- tance study, and VHN for most of them. The extraordi- IurnoructroN nary confusion that has surrounded the quantitative data and qualitative descriptions of theseminerals is described. Cooperite,braggite and vysotskiteare important Reflectancespectra and color valuesdemonstrate the false- sourcesof platinum and palladium in many of the hood of the long-standing belief that cooperite resembles world's largest depositsof platinum-group minerals. pyrrhotine. The (Schneiderhcihn original descriptions It is thus surprising that their optical characteristics, l929a,b) were not probably of cooperitebut of the then. particularly those of cooperite and braggite, have unknown mineral braggite. This error was compounded present, when the reflectance'spectrum' of pyrrhotine, from the remainedill-defined sincetheir discovery.At supposedlycooperite-bearing concentrates, was mistaken theh identificationwith the microscopeis uncertain, for that of cooperite. owing to erroneousand conflicting descriptiveand quantitative data in the literature. Keywords: cooperite, braggite-vysotskite,reflectance spec- We first ericounteredthis problem in 1980when tra, color values,optical characteristics,YHN, composi- examiningsamples from the MinneapolisAdit area tional range, Potgietersrus, Stillwater complex, of the Howland Reef (Bow el ol. 1982), Stillwater platinum-group minerals. Valley, Montana. Here, unusually, all three minerals occur in close associationbut, during our initial SOMMAIRE investigation, we were unable to identify them without the aid of the electronmicroprobe. Indeed, On a mesur6, entre 400 et 700 nm, le spectre de r6flec- at first, we believed cooperite to be a new mineral tance de la cooperitePtS et de la braggite (Pt,Pd)S de la and braggiteto be cooperite.Closer examination of localit6 type, Potgietersrus(Afrique du Sud). Ces specfies, the literature revealedthat the earliestdescriptions ainsi que la description qualitative gxains, des complEtent of cooperite (Schneiderh6hn l929a,b) were on la caractdrisationdes deux esplces amorc€e en 1932par Ban- nister et Hey, On d€crit aussiI'association min6ralogique, material of dubious authenticity. Thesedescriptions, les propri6tds optiques et Iesspectres de rdflectancede coo- and in particular a suggestedsimilarity to pyrrho- perite, braggite et vysotskite PdS du secteur dit Minnea- tine, are completelymisleading. Unfortunately, when polis Adit du complexe de Stillwater (Montana). Les don- cooperite and braggite were characterized@annister n6essur la cooperite et la braggite sont compar6esi celles & Hey 1932), their optical characteristics were not des dchantillons types; vu le manque de donn€espertinen- determined.It remainedfor Edwards et al. (1942) tes sur le mat6riautype de Noril'sk (U.R.S.S.), les obser- briefly to describethe qualitative optical properties vations ici consign6espeuvent servir d caractdriserla vysot- of a type specimen of braggite. The erroneous skite. On pr€senteles resultatsd'analyses d la microsonde descriptions and reflectance data for cooperite 6lectronique pour tous les grains dont on a d6termin6 la r6flectance, et la durete VHN pour la plupart d'entre eux. (Schneiderhdhn1929a, b, Schnederh6hn& Ramdohr On ddcrit la confusion extraordinaire qui 6mane des des- 1931,Frick 1930)and the incompletedata for bragg- criptions, tant qualitatives que quantitatives, de ces espd- ite hinderedthe identificationof the mineralsby ore ces.Les specfiesde rdflectanceet l'6valuation des couleurs microscopy. Thus, although confirmation of their 149 Downloaded from http://pubs.geoscienceworld.org/canmin/article-pdf/23/2/149/3445915/149.pdf by guest on 03 October 2021 150 THE CANADIAN MINERALOGIST identity was certain by X-ray diffraction and Clearly, a thorough re-investigatioi of all three chemicalanalysis, the problem remainedof identify- minerals using procedures recornmendedby the ing the right mineral in the first instance.As a result, COM was overdue.In particular, the confusionsur- until quite recentlycooperite was regarded as a'rar- rounding the color and brightnessof the minerals ity' (Ramdohr 1980),and braggitewas reported to required measurementof the dispersion of their be a 'very rare mineral' (Picot & Johan 1982). reflectancethroughout the visible spectrum and cal- Attention was first drawn to the 'conflicting and culation from thesespectra of unambiguouscolor- overlapping data' for braggite and cooperite by values.More than this, we consideredit essentialto Leonard et ol. (1969),who also noted that adequate relate thesemeasurements to the composition of each quantitative data were lacking. The situation grain that was measured and to obtain X-ray data improved somewhat in the 1970s,when electron for selectedgrains. We were fortunate in having at microprobesand microscope-photometerscapable our disposal the type specimensof cooperite and of measurementsof spectralreflectance became more braggite of Bannister & Hey (1932), as well as the widely available. The first spectral-reflectancedata, intergrown grains of cooperite, braggite and vysot- though restricted to four wavelengthsthat cor- skite from the MinneapolisAdit. The latter, fortui- respondto the perceivedbrightness and color ofthese tously, occur in a matrix consisting predominantly minerals, were those of Cabri (1972)for braggiteand of pyrrhotine, pentlandite and pyrite; hencedirect Schwellnuset ol. (1976)for cooperiteand braggite. comparisonof cooperiteand pyrrhotine was possi- More completespectra and descriptiveinformation ble. What follows, therefore, may be regardedas the were reported by Picot & Johan (1977). Unfor- completion of the characterizationof braggiteand tunately, the spectraand descriptionsfor cooperite cooperite, with additional and more complete data aretransposed in their book and appearas for brag- for vysotskite. g$e (this mistake occurredat an editorial stage;Picot In addition to measuringthe reflectancespectra, & Johan, pers. comm.). Their description of calculating color values, and measuring micro- cooperiteis also in error; it correspondsneither to indentation hardness(VHN) values, we examinedin cooperitenor to braggite. In 1981,Cabri reviewed detail the apparent color, brightness,bireflectance the situation and concludedthat the reflectancespec- and reflectancepleochroism ofthe minerals in plane- tra of braggite neededconfirmation, that those of polarized light, and their rotation tints between cooperite neededredetermination, and that more crossedpolars. This was done not only to complete work was required on the qualitative optical proper- their characterization but to determine whether the ties of vysotskite.The latter, despitethe uncertain qualitative properties alone were sufficiently distinc- propertiesof braggite,had beencharacterized with tive to be used as a meansof identification. minimal optical data in l962by Genkin &ZWaejnt- sev. In 1982,Picot & Johan publishedcharacteris- EXPERIMEI.ITALPROCEDURE tic reflectance spectra and descriptive data for cooperite. Their R spectra for braggite are also All of the Pt-Pd-Ni-S-bearing samplesfrom the characteristic, but their description of this mineral Stillwater Yalley examined (fourteen polished does not correspondto thesespectra; in fact, it is mounts, ten polishedgrain-mounts, and five polished almost identical to the description of thin sections)came from an unusually coarse-grained Schneiderhdhn'scooperite rhat had previouslybeen pegmatiticgabbro from the first cross-cutof the Min- reiteratedin various forms in the diagnostictexts of neapolisAdit. Thesesamples were selectedfrom a Farnham (1931),Ramdohr (1950and all later edi: suiteof specimensBM 1981,134. The equipmentand tions), Schouten(1962)and Uytenbogaardt& Burke polishing procedure used for the mounts and grain (1971).Correct reflectancevalues determined at the mounts were describedin Criddle
Load more

Recommended publications
  • Mineral Profile
    Platinum September 2009 Definition, mineralogy and Pt Pd Rh Ir Ru Os Au nt Atomic 195.08 106.42 102.91 192.22 101.07 190.23 196.97 deposits weight opme vel Atomic Definition and characteristics 78 46 45 77 44 76 79 de number l Platinum (Pt) is one of a group of six chemical elements ra UK collectively referred to as the platinum-group elements Density ne 21.45 12.02 12.41 22.65 12.45 22.61 19.3 (gcm-3) mi (PGE). The other PGE are palladium (Pd), iridium (Ir), osmium e Melting bl (Os), rhodium (Rh) and ruthenium (Ru). Reference is also 1769 1554 1960 2443 2310 3050 1064 na point (ºC) ai commonly made to platinum-group metals and to platinum- Electrical st group minerals, both often abbreviated to PGM. In this su resistivity r document we use PGM to refer to platinum-group minerals. 9.85 9.93 4.33 4.71 6.8 8.12 2.15 f o (micro-ohm re cm at 0º C) nt Chemically the PGE are all very similar, but their physical Hardness Ce Minerals 4-4.5 4.75 5.5 6.5 6.5 7 2.5-3 properties vary considerably (Table 1). Platinum, iridium (Mohs) and osmium are the densest known metals, being significantly denser than gold. Platinum and palladium are Table 1 Selected properties of the six platinum-group highly resistant to heat and to corrosion, and are soft and elements (PGE) compared with gold (Au). ductile. Rhodium and iridium are more difficult to work, while ruthenium and osmium are hard, brittle and almost pentlandite, or in PGE-bearing accessory minerals (PGM).
    [Show full text]
  • New Mineral Names*,†
    American Mineralogist, Volume 104, pages 625–629, 2019 New Mineral Names*,† DMITRIY I. BELAKOVSKIY1 AND FERNANDO CÁMARA2 1Fersman Mineralogical Museum, Russian Academy of Sciences, Leninskiy Prospekt 18 korp. 2, Moscow 119071, Russia 2Dipartimento di Scienze della Terra “Ardito Desio”, Universitá di degli Studi di Milano, Via Mangiagalli, 34, 20133 Milano, Italy IN THIS ISSUE This New Mineral Names has entries for 8 new minerals, including fengchengite, ferriperbøeite-(Ce), genplesite, heyerdahlite, millsite, saranchinaite, siudaite, vymazalováite and new data on lavinskyite-1M. FENGCHENGITE* X-ray diffraction pattern [d Å (I%; hkl)] are: 7.186 (55; 110), 5.761 (44; 113), 4.187 (53; 123), 3.201 (47; 028), 2.978 (61; 135). 2.857 (100; 044), G. Shen, J. Xu, P. Yao, and G. Li (2017) Fengchengite: A new species with 2.146 (30; 336), 1.771 (36; 24.11). Single-crystal X-ray diffraction data the Na-poor but vacancy-dominante N(5) site in the eudialyte group. shows the mineral is trigonal, space group R3m, a = 14.2467 (6), c = Acta Mineralogica Sinica, 37 (1/2), 140–151. 30.033(2) Å, V = 5279.08 Å3, Z = 3. The structure was solved by direct methods and refined to R = 0.043 for all unique I > 2σ(I) reflections. Fengchengite (IMA 2007-018a), Na Ca (Fe3+,) Zr Si (Si O ) 12 3 6 3 3 25 73 Fenchengite is the Fe3+ analog of eudialyte with a structural difference (H O) (OH) , trigonal, is a new eudialyte-group mineral discovered in 2 3 2 in vacancy dominant N5 site and splitting its Na site N1 into N1a and the agpaitic nepheline syenites and its pegmatite facies near the Saima N1b sites.
    [Show full text]
  • STRATIFORM and ALLUVIAL Plafl NUM MINERALIZATION in THE
    LU3 The Canadian M iner alog is t Vol. 33,pp. 1023-lM5(1995) STRATIFORMAND ALLUVIALPLAfl NUM MINERALIZATION IN THENEW CALEDONIA OPHIOLITE COMPLEX THIERRY AUGE lNI PIERREMATIRZOT BRGM'Metallogeny and Geotynarnics", B.P. 6009, 45060 Orldans Cedex 2, France ABSTRA T An unusualtype offt mineralizationhas beenfound in the New Caledoniaophiolite complex, associatedwitl stratiform chromite-bearingrocks at the baseof the cumulateseries (close to the transition zone betweendunite and pyroxene-bearing rocks) and with cbromite-richpyroxenite dykes from the samezone. Two placer deposis, both enrichedin Fl also have been recognized one derived from the chromite-rich horizons and the other a cbromitiferous beach sand of unknown origin. Chromite-bearingrocks aremarked by a very strongenrichment in Pt relative to fhe other platinum-groupelements (PGE), $'ith a rrardmunconcentration of 11.5ppm (average3.9 ppm). The Pt enrichmenttakes the form of platinum-groupminerals (PGM) included in chromite crystals and is interpretedas being pdlrar'/. The following minerals have been identified: ft-Fe{u alloys (isoferroplatinum,tulame€nite, tetraferroplatinum and undeterminedphases), cooperite, laurite, bowieite, malanite, cuprorhodsite,unnamed PGE oxides, and base-metalsulfides with PGE in solid solution. The associatedplacers show a slightly different mineral association,with isoferroplatinum,tulameenite, and rare cooperite,sperrylite, Os-k-Ru alloys and PGE oxides. A more complex paragenesishas been identified in the beach san4 with isoferroplatinum,cooperite, laurite, erlichmanite, Os-Ir-Ru alloys, bowieite, ba$ite, hollingworthire, sperrylite, stibiopalladinite, and unnamed Rh sulfide, Pt-Ru-Rh alloy and PGE oxides. This type of mineralization, which differs markedly from the Os-Ru-h mineralization previously recognized in podiform cbromitite in New Caledonia, shows several analogies with Alaskan-type PGE mineralization.The host chromitite,with typical cumulustextwes, is markedby Ti and Feh emichmentdue to derivationfrom an evolved liquid.
    [Show full text]
  • ECONOMIC GEOLOGY RESEARCH INSTITUTE HUGH ALLSOPP LABORATORY University of the Witwatersrand Johannesburg
    ECONOMIC GEOLOGY RESEARCH INSTITUTE HUGH ALLSOPP LABORATORY University of the Witwatersrand Johannesburg CHROMITITES OF THE BUSHVELD COMPLEX- PROCESS OF FORMATION AND PGE ENRICHMENT J.A. KINNAIRD, F.J. KRUGER, P.A.M. NEX and R.G. CAWTHORN INFORMATION CIRCULAR No. 369 UNIVERSITY OF THE WITWATERSRAND JOHANNESBURG CHROMITITES OF THE BUSHVELD COMPLEX – PROCESSES OF FORMATION AND PGE ENRICHMENT by J. A. KINNAIRD, F. J. KRUGER, P.A. M. NEX AND R.G. CAWTHORN (Department of Geology, School of Geosciences, University of the Witwatersrand, Private Bag 3, P.O. WITS 2050, Johannesburg, South Africa) ECONOMIC GEOLOGY RESEARCH INSTITUTE INFORMATION CIRCULAR No. 369 December, 2002 CHROMITITES OF THE BUSHVELD COMPLEX – PROCESSES OF FORMATION AND PGE ENRICHMENT ABSTRACT The mafic layered suite of the 2.05 Ga old Bushveld Complex hosts a number of substantial PGE-bearing chromitite layers, including the UG2, within the Critical Zone, together with thin chromitite stringers of the platinum-bearing Merensky Reef. Until 1982, only the Merensky Reef was mined for platinum although it has long been known that chromitites also host platinum group minerals. Three groups of chromitites occur: a Lower Group of up to seven major layers hosted in feldspathic pyroxenite; a Middle Group with four layers hosted by feldspathic pyroxenite or norite; and an Upper Group usually of two chromitite packages, hosted in pyroxenite, norite or anorthosite. There is a systematic chemical variation from bottom to top chromitite layers, in terms of Cr : Fe ratios and the abundance and proportion of PGE’s. Although all the chromitites are enriched in PGE’s relative to the host rocks, the Upper Group 2 layer (UG2) shows the highest concentration.
    [Show full text]
  • Thirty-Fourth List of New Mineral Names
    MINERALOGICAL MAGAZINE, DECEMBER 1986, VOL. 50, PP. 741-61 Thirty-fourth list of new mineral names E. E. FEJER Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD THE present list contains 181 entries. Of these 148 are Alacranite. V. I. Popova, V. A. Popov, A. Clark, valid species, most of which have been approved by the V. O. Polyakov, and S. E. Borisovskii, 1986. Zap. IMA Commission on New Minerals and Mineral Names, 115, 360. First found at Alacran, Pampa Larga, 17 are misspellings or erroneous transliterations, 9 are Chile by A. H. Clark in 1970 (rejected by IMA names published without IMA approval, 4 are variety because of insufficient data), then in 1980 at the names, 2 are spelling corrections, and one is a name applied to gem material. As in previous lists, contractions caldera of Uzon volcano, Kamchatka, USSR, as are used for the names of frequently cited journals and yellowish orange equant crystals up to 0.5 ram, other publications are abbreviated in italic. sometimes flattened on {100} with {100}, {111}, {ill}, and {110} faces, adamantine to greasy Abhurite. J. J. Matzko, H. T. Evans Jr., M. E. Mrose, lustre, poor {100} cleavage, brittle, H 1 Mono- and P. Aruscavage, 1985. C.M. 23, 233. At a clinic, P2/c, a 9.89(2), b 9.73(2), c 9.13(1) A, depth c.35 m, in an arm of the Red Sea, known as fl 101.84(5) ~ Z = 2; Dobs. 3.43(5), D~alr 3.43; Sharm Abhur, c.30 km north of Jiddah, Saudi reflectances and microhardness given.
    [Show full text]
  • Platinum Group Minerals in Eastern Brazil GEOLOGY and OCCURRENCES in CHROMITITE and PLACERS
    DOI: 10.1595/147106705X24391 Platinum Group Minerals in Eastern Brazil GEOLOGY AND OCCURRENCES IN CHROMITITE AND PLACERS By Nelson Angeli Department of Petrology and Metallogeny, University of São Paulo State (UNESP), 24-A Avenue, 1515, Rio Claro (SP), 13506-710, Brazil; E-mail: [email protected] Brazil does not have working platinum mines, nor even large reserves of the platinum metals, but there is platinum in Brazil. In this paper, four massifs (mafic/ultramafic complexes) in eastern Brazil, in the states of Minas Gerais and Ceará, where platinum is found will be described. Three of these massifs contain concentrations of platinum group minerals or platinum group elements, and gold, associated with the chromitite rock found there. In the fourth massif, in Minas Gerais State, the platinum group elements are found in alluvial deposits at the Bom Sucesso occurrence. This placer is currently being studied. The platinum group metals occur in specific Rh and Os occur together in minerals in various areas of the world: mainly South Africa, Russia, combinations. This particular PGM distribution Canada and the U.S.A. Geological occurrences of can also form noble metal alloys (7), and minerali- platinum group elements (PGEs) (and sometimes sation has been linked to crystallisation during gold (Au)) are usually associated with Ni-Co-Cu chromite precipitation of hydrothermal origin. sulfide deposits formed in layered igneous intru- In central Brazil there are massifs (Americano sions. The platinum group minerals (PGMs) are do Brasil and Barro Alto) that as yet are little stud- associated with the more mafic parts of the layered ied, and which are thought to contain small PGM magma deposit, and PGEs are found in chromite concentrations.
    [Show full text]
  • The Bushveld Igneous Complex
    The Bushveld Igneous Complex THE GEOLOGY OF SOUTH AFRICA’S PLATINUM RESOURCES By C. A. Cousins, MSC. Johannesburg Consolidated Investment Company Limited A vast composite body of plutonic and volcanic rock in the central part of the Transvaal, the Bushveld igneous complex includes the platinum reef worked by Rustenburg Platinum Mines Limited and constituting the world’s greatest reserve of the platinum metals. This article describes the geological and economic aspects of this unusually interesting formation. In South Africa platinum occurs chiefly in square miles. Two of these areas lie at the the Merensky Reef, which itself forms part of eastern and western ends of the Bushveld and the Bushveld igneous complex, an irregular form wide curved belts, trending parallel to oval area of some 15,000 square miles occupy- the sedimentary rocks which they overlie, and ing a roughly central position in the province dipping inwards towards the centre of the of the Transvaal. A geological map of the Bushveld at similar angles. The western belt area, which provides the largest known has a flat sheet-like extension reaching the example of this interesting type of formation, western boundary of the Transvaal. The is shown on the facing page. third area extends northwards and cuts out- The complex rests upon a floor of sedi- side the sedimentary basin. Its exact relation- mentary rocks of the Transvaal System. This ship to the other outcrops within the basin floor is structurally in the form of an immense has not as yet been solved. oval basin, three hundred miles long and a As the eastern and western belts contain hundred miles broad.
    [Show full text]
  • Detrital Platinum-Group Minerals (PGM) in Rivers of the Bushveld Complex, South Africa – a Reconnaissance Study
    Detrital Platinum-Group Minerals (PGM) in Rivers of the Bushveld Complex, South Africa – A Reconnaissance Study Thomas Oberthür, Frank Melcher, Lothar Gast, Christian Wöhrl and Jerzy Lodziak Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, D-30655 Hannover, Germany e-mail: [email protected] Introduction Regional geology The initial major discovery of platinum in Sampling concentrated on stream the Bushveld Complex, which subsequently led to sediments of rivers in the vicinity of the original the discovery of the Merensky Reef, was made in discovery of the Merensky Reef on the farm 1924 by panning in a river bed on the farm Maandagshoek close to Burgersfort in the Eastern Maandagshoek in the Eastern Bushveld (Merensky Bushveld (Fig. 1). The localities investigated by 1924, 1926, Wagner 1929, Cawthorn 1999a, 1999b, Cawthorn (1999b, 2001), i. e. those documented by 2001). Wagner (1929) also reports on a number of Merensky (1924) as Pt-bearing, and additional alluvial diggings in the Bushveld Complex that places along the Moopetsi river were sampled. The produced some platinum. However, as mining river valley runs approximately north-south, commenced on the rich pipes and reef-type deposits subparallel to the layering of the Mafic Phase of the of the Bushveld, alluvial PGM soon became Bushveld Complex, and is between 2 and 3 km forgotten and no published information on the wide. On the farm Maandagshoek, the Merensky placer PGM is available. Cawthorn (1999b, 2001) Reef and the UG2 are about 2 km apart and crop performed geochemical investigations of stream- out on the western and eastern side, respectively, of sediments at and close to the 1924 discovery site the Moopetsi river.
    [Show full text]
  • Platinum-Group Element and Minerals in the Lower and Middle Group Chromitites of the Western Bushveld Complex, South Africa
    Helmholtz-Zentrum Dresden-Rossendorf (HZDR) Platinum-group element and minerals in the Lower and Middle Group chromitites of the western Bushveld Complex, South Africa Junge, M.; Oberthür, T.; Osbahr, I.; Gutter, P.; Originally published: August 2016 Mineralium Deposita 51(2016)7, 841-852 DOI: https://doi.org/10.1007/s00126-016-0676-6 Perma-Link to Publication Repository of HZDR: https://www.hzdr.de/publications/Publ-26567 Release of the secondary publication based on the publisher's specified embargo time. Platinum-group elements and minerals in the Lower and Middle Group chromitites of the western Bushveld Complex, South Africa Malte Junge1, Thomas Oberthür1, Inga Osbahr2 and Paul Gutter3 1Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, D-30655 Hannover, Germany; [email protected] 2Helmholtz Institute Freiberg for Resource Technology, Halsbrücker Strasse 34, 09599 Freiberg, Germany 3SYLVANIA Platinum Ltd., P.O. Box 976, Florida Hills 1716, South Africa Abstract The chromitites of the Bushveld Complex in South Africa contain vast resources of platinum- group elements (PGE). However, knowledge of the distribution and the mineralogical siting of the PGE in the Lower Group (LG) and Middle Group (MG) chromitite seams of the Bushveld Complex is limited. We studied concentrates from the LG-6 and MG-2 chromitites of the western Bushveld Complex by a variety of microanalytical techniques. The dominant PGM are sulfides, namely laurite, cooperite-braggite and malanite-cuprorhodsite, followed by PGE-sulfarsenides, sperrylite, and Pt-Fe alloys. Laurite is the most abundant PGM (vol%). The matching sets of PGM present in the LG and MG chromitites of both the western and the eastern Bushveld Complex, and in the UG-2 chromitite, show strong similarities which support the assumption of a characteristic and general chromitite-related PGM assemblage.
    [Show full text]
  • Braggite (Pt, Pd, Ni)S
    Braggite (Pt, Pd, Ni)S c 2001-2005 Mineral Data Publishing, version 1 Crystal Data: Tetragonal. Point Group: 4/m or 4. As prisms, to 2 cm, and rounded grains. Twinning: Rarely observed. Physical Properties: Hardness = n.d. VHN = 946–1064, 997 average (100 g load). D(meas.) = ∼10 D(calc.) = 9.383 Optical Properties: Opaque. Color: White in reflected light. Luster: Metallic. Anisotropism: Distinct, in purplish and pinkish shades of gray and brown. R1–R2: (400) 41.3–41.8, (420) 41.8–42.4, (440) 42.1–43.0, (460) 42.4–43.4, (480) 42.5–43.8, (500) 42.7–44.1, (520) 42.7–44.2, (540) 42.6–44.2, (560) 42.5–44.2, (580) 42.4–44.2, (600) 42.3–44.1, (620) 42.2–44.1, (640) 41.9–44.0, (660) 41.9–43.9, (680) 41.9–43.8, (700) 41.5–43.8 Cell Data: Space Group: P 42/m. a = 6.367 c = 6.561 Z = 8 X-ray Powder Pattern: Potgietersrus district, South Africa; can be confused with vysotskite. 2.86 (100), 2.93 (30), 2.64 (30), 1.852 (30), 1.423 (30), 1.713 (20), 1.595 (2) Chemistry: (1) (2) (1) (2) Pt 63.2 62.1 Ni 4.4 2.0 Pd 15.4 19.0 S 17.4 16.9 Total 100.4 100.0 (1) Potgietersrus district, South Africa; by electron microprobe, corresponding to (Pt0.60Pd0.27 Ni0.14)Σ=1.01S1.00. (2) Stillwater complex, Montana, USA; by electron microprobe, corresponding to (Pt0.60Pd0.34Ni0.06)Σ=1.00S1.00.
    [Show full text]
  • Sulfide Minerals in the G and H Chromitite Zones of the Stillwater Complex, Montana
    Sulfide Minerals in the G and H Chromitite Zones of the Stillwater Complex, Montana GEOLOGICAL SURVEY PROFESSIONAL PAPER 694 Sulfide Minerals in the G and H Chromitite Zones of the Stillwater Complex, Montana By NORMAN J PAGE GEOLOGICAL SURVEY PROFESSIONAL PAPER 694 The relationship of the amount, relative abundance, and size of grains of selected sulfide minerals to the crystallization of a basaltic magma UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1971 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS C. B. MORTON, Secretary GEOLOGICAL SURVEY William T. Pecora, Director Library of CongresR catalog-card No. 70-610589 For sale by the Superintendent of Documents, U.S. Government Printin&' Otrice Washin&'ton, D.C. 20402 - Price 35 cents (paper cover) CONTENTS Page Abstract------------------------------------------------------------------------------------------------------------ 1 Introduction________________________________________________________________________________________________________ 1 Acknowledgments--------------------------------------------------------------------------------------------------- 4 Sulfide occurrences-------------------------------------------------------------------------------------------------- 4 Sulfide inclusions in cumulus minerals_____________________________________________________________________________ 4 Fabrtc______________________________________________________________________________________________________ 5 Phase assemblages__________________________________________________________________________________________
    [Show full text]
  • The Geological Occurrence, Mineralogy, and Processing by Flotation of Platinum Group Minerals (Pgms) in South Africa and Russia
    minerals Review The Geological Occurrence, Mineralogy, and Processing by Flotation of Platinum Group Minerals (PGMs) in South Africa and Russia Cyril O’Connor 1,* and Tatiana Alexandrova 2 1 Department of Chemical Engineering, Centre for Minerals Research, University of Cape Town, Cape Town 7701, South Africa 2 Department of Minerals Processing, St Petersburg Mining University, St Petersburg 199106, Russia; [email protected] * Correspondence: [email protected] Abstract: Russia and South Africa are the world’s leading producers of platinum group elements (PGEs). This places them in a unique position regarding the supply of these two key industrial commodities. The purpose of this paper is to provide a comparative high-level overview of aspects of the geological occurrence, mineralogy, and processing by flotation of the platinum group minerals (PGMs) found in each country. A summary of some of the major challenges faced in each country in terms of the concentration of the ores by flotation is presented alongside the opportunities that exist to increase the production of the respective metals. These include the more efficient recovery of minerals such as arsenides and tellurides, the management of siliceous gangue and chromite in the processing of these ores, and, especially in Russia, the development of novel processing routes to recover PGEs from relatively low grade ores occurring in dunites, black shale ores and in vanadium-iron-titanium-sulphide oxide formations. Keywords: Russia; South Africa; PGMs; geology; mineralogy; flotation Citation: O’Connor, C.; Alexandrova, T. The Geological Occurrence, Mineralogy, and Processing by Flotation of Platinum Group Minerals (PGMs) in South 1. Introduction Africa and Russia.
    [Show full text]