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Compositional variation of cooperite, braggite, and vysotskite from the Bushveld Complex

Published online by Cambridge University Press:  05 July 2018

Sabine M. C. Verryn  and
Roland K. W. Merkle
Sabine M. C. Verryn
Affiliation:
Department of Geology, University of Pretoria, Pretoria, 0002 South Africa
Roland K. W. Merkle
Affiliation:
Department of Geology, University of Pretoria, Pretoria, 0002 South Africa
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Abstract

The compositions of coexisting and individual cooperite (ideally PtS) and braggite (ideally (Pt,Pd)S) grains from the Merensky Reef of the Bushveld Complex, as well as cooperite, braggite and vysotskite (ideally PdS) grains from the UG-2 of the Bushveld Complex were investigated. There is a clearly defined miscibility gap between cooperite and braggite, but no evident gap between braggite and vysotskite. Partition coefficients between cooperite and braggite are determined on coexisting phases. The KDbraggite/cooperite in atomic ratios are estimated to be 0.54 for Pt, 15.81 for Pd and 5.93 for Ni. For Rh and Co the KDbraggite/cooperite are estimated to be > 1.40 and > 1.46 respectively. No systematic behaviour is detected for Fe and Cu. Coupled substitutions of Pd + Ni for Pt in cooperite and braggite/vysotskite are indicated. Within the cooperite of the Merensky Reef, the Pd:Ni ratio is approximately 9:11. The substitution trend in braggite, which extends to vysotskite in the UG-2, is dependent on the base-metal sulphide (BMS) association. If pentlandite is the dominant Ni-bearing BMS, the Pd:Ni ratio is about 7:3 in the Merensky Reef and in the UG-2. Millerite as the dominant Ni-bearing BMS in the UG-2 changes this ratio to 3:1. It is concluded that the Ni-content in braggite/vysotskite from BMS assemblages does not depend on the NiS activity, but rather on temperature of formation.

Keywords

cooperitebraggitevysotskiteMerensky ReefBushveld ComplexUG-2
Type
Mineralogy
Information
Mineralogical Magazine , Volume 58 , Issue 391 , June 1994 , pp. 223 - 234
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1994

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References

Bannister, F.A. and Hey, M.H. (1932) Determination of minerals in platinum concentrates from the Transvaal by X-ray methods. Mineral. Mag., 28, 188–206.Google Scholar
Barm, I., Knacke, O. and Kubaschewski, O. (1977) Thermochemical properties of inorganic substances (Supplement). Springer Verlag Berlin, Heidelberg, New York.Google Scholar
Brynard, H. J., de Villiers, J. P. R. and Viljoen, E. A. (1976) A mineralogical investigation of the Merensky Reef at the Western Platinum Mine, near Marikana, South Africa. Econ. Geol., 71, 1299–307.CrossRefGoogle Scholar
Cabri, L. J., Laflamme, J. H. G., Steward, J. M., Turner, K. and Skinner, B. J. (1978) On cooperite, braggite, and vysotskite. Amer. Mineral. 63, 832-9.Google Scholar
Criddle, A. J. and Stanley, J. S. (1985) Characteristic optical data for cooperite, braggite and vysotskite. Canad. Mineral, 23, 149–69.Google Scholar
Genkin, A. D. and Evstigneeva, T. L. (1986) Associations of platinum-group minerals of the NoriFsk copper-nickel sulfide ores. Econ. Geol, 81, 1203–12.CrossRefGoogle Scholar
Halkoaho, T. (1989) Ala-Penikan platinametallimi-neralisaatiot Penikkain kerrosintruusiossa. Raport-ti no 2, Perapohjan platinaprojekti, Oulun Yliopisto, 173 pp.Google Scholar
Kaiser, H. and Specker, H. (1956) Bewertung und Vergleich von Analysenverfahren. Z. anal. Chem., 149, 46–66.CrossRefGoogle Scholar
Kingston, G. A. and El-Dosuky, B. T. (1982) A contribution on the platinum-group mineralogy of the Merensky Reef at the Rustenburg Platinum Mine. Econ. Geol, 71, 1299–307.Google Scholar
Kinloch, E. D. (1982) Regional trends in the platinum-group mineralogy of the Critical Zone of the Bushveld Complex, South Africa. Econ. Geol, 77, 1328–47.CrossRefGoogle Scholar
Kullerud, G. (1963) Thermal stability of pentlandite. Canad. Mineral, 7, 353–66.Google Scholar
Kullerud, G. and Yund, R. A. (1962) The Ni-S system and related minerals. J. Petrol, 3, 126-75.CrossRefGoogle Scholar
Laputina, I. P. and Genkin, A. D. (1975) Minerals of the braggite—vysotskite series. Izomorpizm Mineraly, hdat. Nauka, 146-50 (in Russian).Google Scholar
McLaren, C. H. and De Villiers, J. P. R. (1982) The platinum-group chemistry and mineralogy of the UG-2 chromitite layer of the Bushveld Complex. Econ. Geol, 77, 1348–66.CrossRefGoogle Scholar
Merkle, R. K. W. (1992) Platinum-group minerals in the middle group of chromitite layers at Marikana, western Bushveld Complex: indications for collection mechanisms and postmagmatic modification. Canad. J. Earth Sci., 29, 209–21.CrossRefGoogle Scholar
Merkle, R. K. W. and Verryn, S. M. C. (1991) Coexisting cooperite and braggite — new data. Papers, International Congress on Applied Mineralogy, 1991, Pretoria, South Africa, Paper 61, 17 pp.Google Scholar
Mostert, A. B., Hofmeyr, P. K. and Potgieter, G. A. (1982) The platinum-group mineralogy of the Merensky Reef at the Impala Platinum Mines, Bophuthatswana. Econ. Geol, 77, 1385–94.CrossRefGoogle Scholar
Naldrett, A. J. and Lehmann, J. (1988) Spinel non-stoichiometry as the explanation for Ni-, Cu-and PGE-enriched sulfides in chromitites. In Geopla-tinum ‘87. (H. M. Prichard, P. J. Potts, J. F. W. Bowles and S. J. Cribb, eds.). Elsevier, Amsterdam, 93-109.Google Scholar
Naldrett, A. J., Lehmann, J. and Auge, T. (1989) Spinel non-stoichiometry and reactions between sulphides, with examples from ophiolite com-plexes. In Magmatic sulphides — the Zimbabwe volume. (M. D. Prendergast and M. J. Jones, eds.). The Institution of Mining and Metallurgy, London, 221-7.Google Scholar
Peyerl, W. (1982) The influence of the Driekop dunite pipe on the platinum-group mineralogy of the UG-2 chromitite in its vicinity. Econ. Geol, 77, 1432–8.CrossRefGoogle Scholar
Reid, A. M., le Roex, A. P. and Minter, W. E. L. (1988) Composition of gold grains in the Vaal Placer, Klerksdorp, South Africa. Mineral. Dep., 23, 211-7.CrossRefGoogle Scholar
Schwellnus, J. S. I, Hiemstra, S. A. and Gasparrini, E. (1976) The Merensky Reef at the Atok Platinum Mine and its environs. Econ. Geol., 71, 249–60.CrossRefGoogle Scholar
Skinner, B. J., Luce, F. D., Dill, J. A., Ellis, D. E., Hagen, H. A., Lewis, D. M., Odell, D. A., Sverjensky, D. A. and Williams, N. (1976) Phase relations in ternary portions of the system Pt-Pd-Fe-As-S. Econ. Geol., 71, 1469–75.CrossRefGoogle Scholar
Tarkian, M. (1987) Compositional variations and reflectance of the common platinum-group miner-als. Mineral, and Petrol., 36, 169–90.CrossRefGoogle Scholar
Todd, S. G., Keith, D. W., Le Roy, L. W., Schissel, D. J., Mann, E. L. and Irvine, T. N. (1982) The J-M platinum-palladium reef of the Stillwater Complex, Montana: I. Stratigraphy and petrology. Econ. Geol., 77, 1454–80.CrossRefGoogle Scholar
Vaughan, D. J. and Craig, J. R. (1978) Mineral chemistry of metal sulfldes. Cambridge University Press, xv + 493 pp.Google Scholar
Vermaak, C. F. and Hendriks, L. P. (1976) A review of the mineralogy of the Merensky Reef with specific reference to new data on the precious metal mineralogy. Econ. Geol., 71, 1244–69.CrossRefGoogle Scholar
Volborth, A., Tarkian, M., Stumpfl, E. F. and Housley, R. M. (1986) A Survey of the Pd-Pt mineralization along the 35 km strike of the J-M Reef, Stillwater Complex, Montana. Canad. Mineral.., 24, 329–46.Google Scholar
Von Gruenewaldt, G., Hatton, C. J., Merkle, R. K. W. and Gain, S. B. (1986) Platinum-group element—chromitite associations in the Bushveld Complex. Econ. Geol., 81, 1067–79.CrossRefGoogle Scholar