Titre du document / Document title

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

Auteur(s) / Author(s)

SHCHEKA G. G. ; SOLIANIK A. N. ; LEHMANN B. ; BIENIOK A. ; AMTHAUER G. ; TOPA D. ; LAFLAMME J. H. G. ;

Résumé / 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 Pt^2.64Fe^1.00 to Pt^2.88Fe^1.00 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-homblende-magnetite units of Alaskan-/Uralian-type intrusions.

Revue / Journal Title

Mineralogical Magazine   ISSN 0026-461X   CODEN MNLMBB 

Source / Source

2004, vol. 68, n^o6, pp. 871-885 [15 page(s) (article)]

Langue / Language

Anglais

Editeur / Publisher

Mineralogical Society, London, ROYAUME-UNI  (1969) (Revue)

Localisation / Location

INIST-CNRS, Cote INIST : 3052, 35400012616778.0040