Phase relations in ternary portions of the system Pt-Pd-Fe-As-S

Skinner, Brian J.; Luce, Frederick D.; Dill, J. A.; Ellis, D. E.; Hagan, H. A.; Lewis, D.; Odell, D. A.; Sverjensky, Dimitri A.; Williams, N.K.

doi:10.2113/gsecongeo.71.7.1469

Cited by 46 publications

(24 citation statements)

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“…The phase chemistry of platinum bismuthinides, bismutotellurides and tellurides (Cabri 1981) suggests that they should decompose at relatively low temperatures and thus be available for transport, even at conditions of moderately low-grade metamorphism. Their genesis has been attributed either to late magmatic fractionation of the PGE (Cabri & Laflamme 1976, Skinner et al 1976 or to remobilization of the PGE during a later hydrothermal stage (e.g., Ballhaus & Stumpfl 1986).…”

Section: Platinum-group Minerals and Base-metal Sulfidesmentioning

confidence: 99%

PGE AND Ag MINERALIZATION IN A BRECCIA ZONE OF THE PRECAMBRIAN NUASAHI ULTRAMAFIC-MAFIC COMPLEX, ORISSA, INDIA

Mondal¹,

Baidya²,

Rao³

et al. 2001

The Canadian Mineralogist

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The Nuasahi ultramafic-mafic complex, in Orissa, India, contains high concentrations of platinum-group elements (Pt up to 9.6 ppm, Pd up to 17.9 ppm) and Ag (up to 6.6 ppm) in a chromiferous sulfide-rich breccia zone. The plutonic complex occurs within an Archean belt of supracrustal rocks. The complex consists of an ultramafic unit in fault contact with and overlain by gabbros whose stratigraphic top is characterized by a zone of brecciation. Lode chromite deposits occur in the ultramafic suite and are currently being mined. Magnesiochromite compositions in the lodes are refractory and show little variation within the ultramafic suite (Cr 2 O 3 ~60%, Al 2 O 3 ~12%, MgO ~15%). Sudburyite, (Pd,Bi)Sb, members of the michenerite-testibiopalladite series, and irarsite-hollingworthite (IrAsS-RhAsS) are the common platinum-group minerals (PGM) in the chromite-sulfide assemblage of the breccia zone. Sudburyite is preferentially included within coarse-grained ferrian chromite, along with numerous inclusions of chalcopyrite, pyrrhotite, rutile, ilmenite and oriented lamellae of clinochlore. The distinctive noble-metal composition (high Pd, Pt and Ag with high Cu) and dominant Pd-Bi-Te-Sb-bearing PGM in the mineralized portion indicate its evolved nature. Mineralization developed by magmatic processes; a hybrid magma resulting from partial incorporation of serpentinized chromite-bearing ultramafic rocks and chromitite in the younger gabbroic magma was emplaced within the preexisting breccia zone. The breccia zone developed during brittle deformation along a NNW-trending shear zone.Keywords: ultramafic complex, breccia zone, chromite, sulfides, platinum-group element mineralization, inclusions, platinumgroup minerals, Nuasahi, Orissa, India. SOMMAIRELe complexe ultramafique-mafique de Nuasahi, à Orissa, en Inde, contient des concentrations élevées des éléments du groupe du platine (juqu'à 9.6 ppm de Pt, 17.9 ppm de Pd) et d'argent (jusqu'à 6.6 ppm) dans une zone brécifiée enrichie en spinelle chromifère et en sulfures. Le complexe plutonique est situé dans une ceinture de roches archéennes d'origine supracrustale. Il contient une unité ultramafique en contact tectonique avec une unité supérieure gabbroïque dont le sommet est bréchifié. Les gisements in situ de spinelle chromifère se trouvent dans la suite ultramafique, et sont présentement exploités. La composition de la magnésiochromite est réfractaire et varie peu dans la suite ultramafique (Cr 2 O 3 ~60%, Al 2 O 3 ~12%, MgO ~15%). Parmi les minéraux du groupe du platine, on trouve sudburyite (Pd,Bi)Sb, des membres de la série michenerite-testibiopalladite, et irarsitehollingworthite (IrAsS-RhAsS) associés au spinelle chromifère et aux sulfures de la zone bréchifiée. La sudburyite se présente surtout en inclusions dans la chromite ferrique à grains grossiers, de même que chalcopyrite, pyrrhotite, rutile, ilménite, et clinochlore en lamelles orientées. L'enrichissement distinctif en métaux nobles (Pd, Pd, Pt et Ag avec Cu élevé) et la dominance de minéraux du grou...

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Section: Platinum-group Minerals and Base-metal Sulfidesmentioning

confidence: 99%

PGE AND Ag MINERALIZATION IN A BRECCIA ZONE OF THE PRECAMBRIAN NUASAHI ULTRAMAFIC-MAFIC COMPLEX, ORISSA, INDIA

Mondal¹,

Baidya²,

Rao³

et al. 2001

The Canadian Mineralogist

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“…In Table 7 the respective values for a and b for Pt, Pd and Ni, with their standard errors, are presented together with Spearman correlation coefficients. As the values of the 36 grains used for calculations in Table 7 are already mean values of a number of spot analyses, the standard deviations indicated in Table 7 (Skinner et aL, 1976) and 970~ (Barin et al, 1977) are reported. At 800~ the braggite-like solid solution ranges from PdS to 0ado.76Pto.24)S. The Ni-free projected data from our samples of the Merensky Reef, as well as the UG-2, indicate cooperite to range from PtS to (Pto.94Pd0.o6)S and braggite from (Pto.74Pdo.26)S to PdS in the case of the UG-2.…”

Section: Partition Coefficientsmentioning

confidence: 99%

“…Although cooperite (ideally PtS) and braggite (ideally (Pt,Pd)S) have been synthesized by Skinner et al (1976) at 1000~ and cooperite, braggite, and vysotskite (ideally PdS) by Cabri et al (1978) at 800~ in the Ni-free system, analyses of natural cooperite, braggite, and vysotskite typically contain significant amounts of Ni.…”

Section: Introductionmentioning

confidence: 99%

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

Verryn

Merkle

1994

Mineral. mag.

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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 gbD raggite/c~176 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/~D ~ 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.

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“…Experimental investigations by Skinner et al (1976) at 1000°C and Cabri et al (1978 at 800°C concentrated on the PtS-PdS join; these authors did not explore the possible influence of Ni on thermal stabilities and miscibility ranges of minerals in the system. The system Pd-Fe-Ni-S was investigated by Makovicky et al (1990) and Makovicky & KarupMøller (1995); the influence of Pt, however, has not been assessed.…”

Section: Related Experimental Investigationsmentioning

confidence: 99%

THE SYSTEM PtS PdS NiS BETWEEN 1200 AND 700 C

Verryn¹,

Merkle²

2002

The Canadian Mineralogist

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Results of experimental investigations in the dry system PtS-PdS-NiS between 1200° and 700°C are presented. The phases encountered in the experimental runs are synthetic cooperite [(Pt,Pd,Ni)S], synthetic braggite [(Pt,Pd,Ni)S], synthetic vysotskite [(Pd,Pt,Ni)S], quenched sulfide liquid, and Ni 1-x S. Synthetic cooperite is stable to temperatures above 1200°C, whereas synthetic braggite is stable at temperatures below 1100°C, and synthetic vysotskite, below 1000°C. Below 900°C in the system PtS-PdSNiS, Ni-saturated synthetic cooperite, braggite, and vysotskite coexist with Ni 1-x S. At 900°C, only Ni-saturated, Pd-free synthetic cooperite coexists with Ni 1-x S, and synthetic braggite and Pd-bearing synthetic cooperite coexist with a Pd-Ni-Pt sulfide melt. At temperatures ≥ 1000°C, Ni-saturated synthetic cooperite and braggite coexist with a Pd-Ni-Pt sulfide melt. In the experiments, there is a clearly defined miscibility-gap between cooperite and braggite, but no gap was observed between braggite and vysotskite. The Ni content of braggite and vysotskite with varying Pt:Pd ratio in a Ni-saturated environment is a function of temperature. A higher Ni content indicates a lower temperature of equilibration, and can be estimated using the following equation

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Phase relations in ternary portions of the system Pt-Pd-Fe-As-S

Cited by 46 publications

References 0 publications

PGE AND Ag MINERALIZATION IN A BRECCIA ZONE OF THE PRECAMBRIAN NUASAHI ULTRAMAFIC-MAFIC COMPLEX, ORISSA, INDIA

PGE AND Ag MINERALIZATION IN A BRECCIA ZONE OF THE PRECAMBRIAN NUASAHI ULTRAMAFIC-MAFIC COMPLEX, ORISSA, INDIA

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

THE SYSTEM PtS PdS NiS BETWEEN 1200 AND 700 C

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