Platinum-group minerals in the Hitura nickel deposit, Finland

Abstract

The northern part of the Hitura serpentinite-peridotite body contains Ni-Cu mineralization whose grade is highest in the contact zone. Pt metals average 0.027 g/ton Pt and 0.048 g/ton Pd in the ultramafic body. A detailed microscopic, microprobe, and analytical study of the Pt metals and minerals reveals that sperrylite is the only independent Pt mineral. Of the Pd minerals, michenerite and Pd-bearing irarsite, as well as an unnamed Bi-bearing nickel telluride resembling melonite, have been recognized and analyzed. The tenor of Ir and Rh is generally below the limit of detection, although homoaxial, zonal intergrowths of irarsite, hollingworthite, and nickelian cobaltite have been encountered in Pt- and Pd-rich samples.An R-mode factor analysis was applied to the analytical data to establish the mutual relationships between the base metals and the metals of the platinum group. The distribution of the platinum metals coincides rather well with that of the sulfides, although in detail platinum is enriched in certain tectonic zones close to sulfide mineralization. Palladium shows a marked correlation with pyrrhotite-pentlandite mineralization, but Pd together with Ag is also enriched in chalcopyrite-rich veins and breccia ore.