DOCSLIB.ORG

Platinum-Group Element Distribution in Base- Metal Sulfides of the Merensky Reef and UG2 from the Eastern and Western Bushveld Complex, South Africa

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Platinum-Group Element Distribution in Base- Metal Sulfides of the Merensky Reef and UG2 from the Eastern and Western Bushveld Complex, South Africa PhD thesis Inga Osbahr Platinum-group element distribution in base- metal sulfides of the Merensky Reef and UG2 from the eastern and western Bushveld Complex, South Africa (Platingruppenelement - Verteilung in Sulfiden des Merensky Reef und UG2 im Bushveld Komplex, Südafrika) Der Naturwissenschaftlichen Fakultät der Friedrich-Alexander-Universität Erlangen-Nürnberg zur Erlangung des Doktorgrades Dr. rer. nat. Vorgelegt von Inga Osbahr aus Berlin PhD thesis Inga Osbahr Als Dissertation genehmigt von der Naturwissenschaftlichen Fakultät der Friedrich-Alexander-Universität Erlangen-Nürnberg Tag der mündlichen Prüfung: 09.08.2012 Vorsitzender der Promotionskommission: Prof. Dr. Rainer Fink Erstberichterstatter: Prof. Dr. Reiner Klemd Zweitberichterstatter: Prof. Dr. Karsten Haase PhD thesis Inga Osbahr ZUSAMMENFASSUNG Buntmetall-Sulfide (BMS) sind wichtige Träger von Platingruppenelementen (PGE) in magmatischen Ni-Cu-PGE Lagerstätten. Die Verteilung und Konzentration von PGE in Pentlanditen, Pyrrhotinen, Chalkopyriten und Pyriten wurde an Proben des Merensky Reef und des UG2 aus dem westlichen und östlichen Bushveld Komplex in Südafrika untersucht. An insgesamt vier Bohrkernen aus dem Merensky Reef und zwei Bohrkernen aus dem UG2 wurden ausgewählte Buntmetall-Sulfide analysiert. Diese Sulfide stammen aus dem mineralisierten Bereich des Merensky Reef und des UG2. Zur Bestimmung der Hauptelemente wurden Elektronenstrahlmikrosonden-Analysen durchgeführt und zur Bestimmung der Spurenelemente (PGE, Ag und Au) Laser Ablation-Inductively Coupled Plasma- Mass Spektrometer (LA-ICP-MS)-Analysen. Zusätzlich wurden Gesamt- gesteinsanalysen an repräsentativen Proben durchgeführt. Die Verteilung von Pt und Pd im Gesamtgestein des Merensky Reef des westlichen Bushveld Komplexes zeigt eine sogenannte „top-loaded“ Mineralisation, was bedeutet, dass die höchsten PGE-Konzentrationen befinden sich im Bereich des oberen Chromititbands und seiner direkten Umgebung. Im östlichen Bushveld Komplex hingegen ist die Verteilung komplexer, da die maximalen Pt- und Pd-Konzentrationen im Merensky Reef auf das untere und obere Chromititband verteilt sind. Im UG2 sind die höchsten Konzentrationen von Pt und Pd auf den unteren und oberen Bereich des UG2 Chromitit beschränkt. Die Ergebnisse der LA-ICP-MS Analysen zeigen, dass die PGE am stärksten im Pentlandit angereichert sind, wohingegen Pyrrhotin deutlich geringere PGE-Gehalte aufweist und im Chalkopyrit kaum nachweisbare PGE-Konzentrationen enthalten sind. Pentlandit, sowohl aus dem Merensky Reef, als auch aus dem UG2, enthält wesentliche Pd- und Rh- Konzentrationen. Pentlandite im Merensky Reef des östlichen Bushveld Komplex zeigen Konzentrationen von bis zu 700 ppm Pd und bis zu 130 ppm Rh. Im westlichen Bushveld wurden im Pentlandit sogar bis zu 1750 ppm Pd und 1000 ppm Rh nachgewiesen. Pyrrhotin kann deutliche Konzentrationen von IPGE (bis zu je 33 ppm Ru, Os und Ir) aufweisen. Chalkopyrit enthält geringe PGE-Konzentrationen, kann aber hohe Silbergehalte (bis zu 50 ppm) aufweisen. Im UG2 des westlichen Bushveld Komplex können im Pentlandit bis zu 400 ppm Pd und 200 ppm Rh nachgewiesen werden, im östlichen Bushveld können es sogar bis zu 1000 ppm Pd und 140 ppm Rh sein. Auch deutliche Gehalte von Ir (150 ppm) und Ru (175 ppm) wurden gemessen. Auch im UG2 enthält der Chalkopyrit kaum nachweisbare PGE-Konzentrationen, eine Ausnahme bildet das Pt, welches in wenigen Proben bis zu 20 ppm erreichen kann. PhD thesis Inga Osbahr Aus einer Massenbilanzierung wird ersichtlich, dass Pentlandit aus dem feldspatführenden Pyroxenit und dem pegmatoidalen feldspatführenden Pyroxenit des Merensky Reef bis zu 100 % des Pd und Rh einbaut, ebenso 10-40 % des Os, Ir und Ru. Pyrrhotin und Chalcopyrit enthalten weniger als 10 % der im Gesamtgestein enthaltenen PGE. Die übrigen PGE (darunter bis zu 100 % des Platins) sitzen in Platingruppenmineralen, wie Cooperit/Braggit, Moncheit, Sperrylit und Isoferroplatinum. Im UG2 des westlichen Bushveld Komplex sind nur ca. 5 % des gesamten Pd und 15 % des gesamten Rh im Pentlandit eingebaut. Im östlichen Bushveld sind es bis zu 40 % des Pd und 30 % des Rh und insgesamt weniger als 20 % des Os, Ir und Ru. Ähnlich wie im Merensky Reef liegen, auch im UG2, fast 100 % des Platins in Form von diskreten Platingruppenmineralen vor. Im Merensky Reef des Bushveld Komplex zeigt die Verteilung von Cu, Ni und S gegenüber Pd und Pt sogenannte „offsets patterns“. Das Verteilungsmuster dieser „offsets“ entspricht vom Liegendem zum Hangendem: Pd in pentlandite → Pd/Pt im Gesamtgestein → (Cu, Ni, S) im Gesamtgestein. Diese Abfolge konnte für einen Großteil der Sequenzen beobachtet werden. Die höchste Pd Konzentration im Pentlandit scheint an die früheste, volumenmäßig aber eher geringe sulfidische Schmelze, gebunden zu sein, welche sich im Liegenden des Merensky Reef befindet. Eine mögliche Erklärung für das Auftreten von „offset patterns“ bietet die Rayleigh Fraktionierung. PhD thesis Inga Osbahr ABSTRACT Base-metal sulfides (BMS) in magmatic Ni-Cu-PGE deposits are important carriers of platinum-group elements (PGE). The distribution and concentrations of PGE in pentlandite, pyrrhotite, chalcopyrite and pyrite were determined in samples from the mineralized proportion of four Merensky Reef and two UG2 intersections from the eastern and western Bushveld Complex. Electron microprobe analysis was used for major elements, and in situ LA-ICP-MS for trace elements (PGE, Ag and Au). Whole-rock trace element analyses were performed on representative samples to obtain mineralogical balances. Both Pt and Pd in Merensky Reef samples from the western Bushveld show a “top loaded” mineralization, mainly concentrated in the upper chromitite stringer and its immediate vicinity. Samples from the eastern Bushveld reveal more complex distribution patterns, since the concentration maxima are located in the lower and upper chromitite stringer area. In UG2 samples of the eastern and western Bushveld, the highest Pd and Pt concentrations are located in the lower and upper portion of the UG2 chromitite. In situ LA-ICP-MS analyses of PGE in sulfides reveal that pentlandite carries the highest and most distinctly elevated PGE contents, whereas pyrrhotite and chalcopyrite contain very low PGE concentrations. Pentlandite is the principal host of Pd and Rh in the ores of the Merensky Reef and UG2, being incorporated in the crystal lattice. Palladium and Rh concentrations in pentlandite reach up to 700 ppm and 130 ppm, respectively, in the Merensky Reef samples from the eastern Bushveld, and up to 1750 ppm Pd and 1000 ppm Rh in those from the western Bushveld. Only traces of Pt are found in the BMS. Pyrrhotite contains significant, though generally lower amounts of Ru, Os and Ir, but hardly any Pd or Rh. Chalcopyrite contains most of the Ag but carries extremely low PGE concentrations. In the UG2 samples, Pd and Rh in pentlandite reach up to 400 ppm and 200 ppm, respectively, in the western Bushveld and up to 1000 ppm Pd and 140 ppm Rh in the eastern Bushveld Complex. Significant amounts of Ir (150 ppm) and Ru (175 ppm) were found in the UG2 samples. Pyrrhotite contains significant amounts of Rh (100 ppm), Os (70 ppm) and Ru (200 ppm). Chalcopyrite contains very low PGE concentrations, although maximum Pt concentrations of 20 ppm were detected. Mass balance calculations performed on the Merensky Reef samples reveal that in general, pentlandite in the feldspathic pyroxenite and the pegmatoidal pyroxenite hosts up to 100 % of the Pd and Rh and smaller amounts (10-40 %) of the Os, Ir and Ru. Pyrrhotite and chalcopyrite usually contain less than 10 % of the whole-rock PGE. The remaining PGE concentrations, and especially most of the Pt (up to 100 %), are present in the form of PhD thesis Inga Osbahr discrete platinum-group minerals (PGM) such as cooperite/braggite, sperrylite, moncheite and isoferroplatinum. In the UG2 of the western Bushveld pentlandite hosts 5 % of the whole-rock Pd and 15 % of the whole-rock Rh while in the eastern Bushveld it is 40 % of the Pd and 30 % of the Rh. Less than 20 % of whole-rock Os, Ir and Ru is incorporated in the pentlandite of the UG2. Similar to the Merensky Reef, in the UG2 the remaining PGE and almost 100 % of the Pt are present in the form of discrete platinum-group minerals. Distribution patterns of whole-rock Cu, Ni and S versus whole-rock Pd and Pt commonly show distinct offsets in the Merensky Reef. The general sequence of “offset patterns” of PGE and BMS maxima, in order from bottom to top, is Pd in pentlandite → Pd/Pt in whole-rock → (Cu, Ni, S) in whole-rock, and is quite obvious in most of our samples. Occasionally, only partially similar or more complex trends are also present. Generally, however, the highest Pd concentrations in pentlandite appear to be related to the earliest, volumetrically rather small sulfide liquids, found at the base of the Merensky Reef sequence. A possible explanation for the offset patterns may be Rayleigh fractionation. PhD thesis Inga Osbahr Table of Contents 1. Aim of this Study 10 2. Introduction 11 2.1 The Bushveld Complex 11 2.2 Stratigraphy 15 2.2.1 Merensky Reef 15 2.2.2 UG2 17 2.3 Platinum-group elements 18 2.4 Previous studies on sulfide liquid fractionation 19 3. Sample Description and Petrography 21 3.1 Merensky Reef 21 3.2 UG2 25 4. Analytical Methods 28 4.1 Transmitted and reflected light microscopy 28 4.2 Electron microprobe analyses (EMPA) 28 4.3 Laser ablation-ICP-MS 29 4.4 Electric pulse disaggregation (EPD) and Hydroseparation (HS) 33 4.5 Ni-fire assay 34 5. Mineral Chemistry 35 5.1 Merensky Reef 35 5.1.1 Orthopyroxene 35 5.1.2 Clinopyroxene 35 5.1.3 Plagioclase 37 5.1.4 Phlogopite 38 5.1.5 Olivine 38 5.1.6 Chromite 39 5.1.7 Pentlandite 41 5.1.8 Chalcopyrite 46 5.1.9 Pyrrhotite and troilite 46 5.1.10 Pyrite 47 5.1.11 Cubanite 47 5.1.12 Platinum-group minerals 50 5.2 UG2 60 5.2.1 Orthopyroxene 60 5.2.2 Clinopyroxene 61 PhD thesis Inga Osbahr 5.2.3 Plagioclase 61 5.2.4 Phlogopite 62 5.2.5 Olivine 62 5.2.6 Chromite 63 5.2.7 Pentlandite 66 5.2.8 Chalcopyrite 69 5.2.9 Cubanite 69 5.2.10 Troilite 70 5.2.11 Platinum-group minerals 70 6.
Load more

Recommended publications
  • 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]
  • 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]
  • Geological Investigations in the Bird River Sill, Southeastern Manitoba (Part of NTS 52L5): Geology and Preliminary Geochemical Results by C.A
    GS-19 Geological investigations in the Bird River Sill, southeastern Manitoba (part of NTS 52L5): geology and preliminary geochemical results by C.A. Mealin1 Mealin, C.A. 2006: Geological investigations in the Bird River Sill, southeastern Manitoba (part of NTS 52L5): geology and preliminary geochemical results; in Report of Activities 2006, Manitoba Science, Technology, Energy and Mines, Manitoba Geological Survey, p. 214–225. Summary and gravitational differentiation. In 2005, this study was initiated to examine the Bird Theyer (1985) identified unusual River Sill (BRS), a mafic-ultramafic layered intrusion cooling conditions requiring several magma pulses and located in the Bird River greenstone belt in southeastern cast doubt on a single magmatic intrusion theory. Manitoba. The BRS is currently an exploration target In 2005, this study was initiated to examine the for Ni-Cu–platinum group element (PGE) deposits and, controls on Ni-Cu-PGE mineralization and test the single in the past, hosted two Ni-Cu mines (Maskwa West and versus multiple injection hypothesis to establish the Dumbarton mines). relationship between mineralization and the magmatic Nickel-copper mineralization on the western half history. Specific objectives include of the BRS consists primarily of disseminated to blebby • detailed mapping of the Chrome, Page, Peterson pyrrhotite+chalcopyrite and is present in the ultramafic Block and National-Ledin properties (Figure GS-19-1); series of the Chrome and Page properties and the mafic • determination of the sulphur source for the Ni-Cu- series of the Wards property. During this study, several PGE mineralization; new sulphide-bearing localities in both the ultramafic and • delineation of the sill’s sulphur saturation history; mafic units of the sill have been identified.
    [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]
  • Origin of Platinum Group Minerals (PGM) Inclusions in Chromite Deposits of the Urals
    minerals Article Origin of Platinum Group Minerals (PGM) Inclusions in Chromite Deposits of the Urals Federica Zaccarini 1,*, Giorgio Garuti 1, Evgeny Pushkarev 2 and Oskar Thalhammer 1 1 Department of Applied Geosciences and Geophysics, University of Leoben, Peter Tunner Str.5, A 8700 Leoben, Austria; [email protected] (G.G.); [email protected] (O.T.) 2 Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Science, Str. Pochtovy per. 7, 620151 Ekaterinburg, Russia; [email protected] * Correspondence: [email protected]; Tel.: +43-3842-402-6218 Received: 13 August 2018; Accepted: 28 August 2018; Published: 31 August 2018 Abstract: This paper reviews a database of about 1500 published and 1000 unpublished microprobe analyses of platinum-group minerals (PGM) from chromite deposits associated with ophiolites and Alaskan-type complexes of the Urals. Composition, texture, and paragenesis of unaltered PGM enclosed in fresh chromitite of the ophiolites indicate that the PGM formed by a sequence of crystallization events before, during, and probably after primary chromite precipitation. The most important controlling factors are sulfur fugacity and temperature. Laurite and Os–Ir–Ru alloys are pristine liquidus phases crystallized at high temperature and low sulfur fugacity: they were trapped in the chromite as solid particles. Oxygen thermobarometry supports that several chromitites underwent compositional equilibration down to 700 ◦C involving increase of the Fe3/Fe2 ratio. These chromitites contain a great number of PGM including—besides laurite and alloys—erlichmanite, Ir–Ni–sulfides, and Ir–Ru sulfarsenides formed by increasing sulfur fugacity. Correlation with chromite composition suggests that the latest stage of PGM crystallization might have occurred in the subsolidus.
    [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]
  • 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]
  • A Specific Gravity Index for Minerats
    A SPECIFICGRAVITY INDEX FOR MINERATS c. A. MURSKyI ern R. M. THOMPSON, Un'fuersityof Bri.ti,sh Col,umb,in,Voncouver, Canad,a This work was undertaken in order to provide a practical, and as far as possible,a complete list of specific gravities of minerals. An accurate speciflc cravity determination can usually be made quickly and this information when combined with other physical properties commonly leads to rapid mineral identification. Early complete but now outdated specific gravity lists are those of Miers given in his mineralogy textbook (1902),and Spencer(M,i,n. Mag.,2!, pp. 382-865,I}ZZ). A more recent list by Hurlbut (Dana's Manuatr of M,i,neral,ogy,LgE2) is incomplete and others are limited to rock forming minerals,Trdger (Tabel,l,enntr-optischen Best'i,mmungd,er geste,i,nsb.ildend,en M,ineral,e, 1952) and Morey (Encycto- ped,iaof Cherni,cal,Technol,ogy, Vol. 12, 19b4). In his mineral identification tables, smith (rd,entifi,cati,onand. qual,itatioe cherai,cal,anal,ys'i,s of mineral,s,second edition, New york, 19bB) groups minerals on the basis of specificgravity but in each of the twelve groups the minerals are listed in order of decreasinghardness. The present work should not be regarded as an index of all known minerals as the specificgravities of many minerals are unknown or known only approximately and are omitted from the current list. The list, in order of increasing specific gravity, includes all minerals without regard to other physical properties or to chemical composition. The designation I or II after the name indicates that the mineral falls in the classesof minerals describedin Dana Systemof M'ineralogyEdition 7, volume I (Native elements, sulphides, oxides, etc.) or II (Halides, carbonates, etc.) (L944 and 1951).
    [Show full text]
  • HAZEL M. PRICHARD Department of Earth Sciences, Open University, Milton Keynes, Buekinghamshire, U.K
    Canadian Mineralogist Vol. 26, pp. 979-990 (1988) PLATINUM AND PALLADIUM MINERALS FROM TWO PGE-RICH LOCALITIES IN THE SHETLAND OPHIOLITE COMPLEX HAZEL M. PRICHARD Department of Earth Sciences, Open University, Milton Keynes, Buekinghamshire, U.K. MK7 6AA MAHMUD TARKIAN Mineralogiseh-Petrographisehes Institut, Grindelallee48, 2000 Hamburg 13, West Germany ABSTRACT INTRODUCTION The mineralogy of Pt- and Pd-bearing platinum-group Traditionally, the PGM considered typical of minerals (POM), which form a varied assemblage previ- ously un described from other ophiolite complexes, is ophiolite complexes are Os-, Ir- and Ru-bearing recorded from two localities in the Shetland ophiolite, Scot- (Constantinides et al. 1979, Talkington 1981, land. In order of abundance the minerals include sperry- Prichard et al. 1981, Legendre 1982, Auge 1985) and lite, mertieite or stibiopalladinite, Pt-Pd-Cu-Au alloys, are associated with chromitites. Pt and Pd com- hongshiite, genkinite and potarite. All six platinum-group pounds may be more common; for example, sper- elements (POE) form major components of minerals in the rylite has been described from northern Tibet (Yu Shetland ophiolite complex. The different POM occur in & Chou 1979), and one sperrylite grain has been ten- association with "each other. Textural evidence indicates that tatively identified from the Josephine peridotite Ru- and Os-bearing POM formed early and were followed by Ir, Pd-, Rh- and, finally, Pt-bearing POM. The con- (Stockman & Hlava 1984). Chang et al. (1973) have reported the presence of sperrylite and stibiopal- centration of all six POE could be magmatic, but much of the POE mineralogy, except for laurite in the center of ladinite in ophiolites in northwestern China.
    [Show full text]