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Euhedral crystals of ferroan platinum, cooperite and mertieite-II from alluvial sediments of the Darya river, Aldan Shield, Russia

Published online by Cambridge University Press:  05 July 2018

G. G. Shcheka*
Affiliation:
Far East Geological Institute, Russian Academy of Sciences, 159 Prospect 100-letya, Vladivostok 690022, Russia Institute of Mineralogy and Mineral Resources, Technical University of Clausthal, Adolph-Roemer-Strasse 2a, D-38678 Clausthal-Zellerfeld, Germany
A. N. Solianik
Affiliation:
Far East Geological Institute, Russian Academy of Sciences, 159 Prospect 100-letya, Vladivostok 690022, Russia
B. Lehmann
Affiliation:
Institute of Mineralogy and Mineral Resources, Technical University of Clausthal, Adolph-Roemer-Strasse 2a, D-38678 Clausthal-Zellerfeld, Germany
A. Bieniok
Affiliation:
Institute of Mineralogy, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
G. Amthauer
Affiliation:
Institute of Mineralogy, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
D. Topa
Affiliation:
Institute of Mineralogy, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
J. H. G. Laflamme
Affiliation:
Mining and Mineral Sciences Laboratories, Canada Centre for Mineral and Energy Technology, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada
*

Abstract

Idiomorphic crystals (up to 3.5 mm) of ferroan platinum, cooperite and mertieite-II were found in a heavy-mineral concentrate from stream sediments of the Darya river in the Aldan Shield, Russia. Pt-Fe crystals display cubic and thin platy habits; occasionally they are twinned. The chemical composition ranges from Pt2.64Fe1.00 to Pt2.88Fe1.00 with Os, Ru, Ir, Rh and Pd below the analytical detection limit of the electron microprobe. X-ray diffractometry of Pt-Fe crystals suggests a F-centred cubic lattice, characteristic of ferroan platinum. Some of the ferroan platinum crystals have large (about 100 μm wide) cooperite overgrowth rims or are covered by a Au-Ag alloy. Cooperite also occurs as large euhedral crystals (up to 3 mm across, partly twinned). Crystals of mertieite-II are speckled with μm-sized (2–5 μm) inclusions of sperrylite and intergrown with minerals of cooperite-braggite solid solution, Pt-Pd-Hg alloy, keithconnite and Au-Ag alloy. Fractures along crystallographic planes of the mertieite-II crystals are filled with Pd-Pt-Fe-Sb-As-Hg-Te-Bi-bearing oxides. The coarse-grained PGM from the Darya have a geological setting similar to the Kondyor PGE placer 75 km to the northeast and are probably related to clinopyroxenite-hornblende-magnetite units of Alaskan-/Uralian-type intrusions.

Information

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2004

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