Intermetallides and alloys of copper and palladium in gold-palladium ores of Skaergaard massif (Greenland)

N. S. Rudashevsky, V. N. Rudashevsky, T. F. D. Nielsen

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2015. V. 144. N 1. P. 30-53

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Language: Russian

Abstract

Different alloys and intermetallides of Cu and Pd were identified in 2314 grains from Au-Pd ores of the Skaergaard layered gabbro massif. As the result of their 1680 microprobe analyses there were identified such minerals: skaergaardite PdCu, nielsenite PdCu₃, (Cu,Pd)_β, (Cu,Pd)_α, (Pd,Cu,Au,Pt) alloys and the native palladium. The paper displays data on average compositions and different chemical varieties of these minerals, as well as on the vertical and lateral zoning in distribution of these precious metal minerals. The primary Pd-Cu alloys were formed within wide range of temperatures in general simultaneously with crystallization and cooling of the matrix gabbro in close connection with separation of a Fe-Cu sulfide melt. Platinum-group elements and gold were selectively concentrated in the Fe-Cu sulfide phase in forms of Pd-Cu and Cu-Au alloys during crystallization of gabbro saturated with a supercritical hydrous fluid enriched in iron, heavy and precious metals.

Key words: intermetallides, 3D mineralogical technology, skaergaardite, nielsenite, Pd-Cu-bearing alloys, native palladium, hydro-silicate «drops-nipples», vertical and lateral zoning, the mineralization genesis.