Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

The Mt. Rudnaya Mss-Iss fine-grained ores from a NE termination of Norilsk 1 deposit were analyzed using a combination of X-ray computed micro tomography, spectral X-ray computed micro tomography and scanning electron microscopy to achieve both, 2D and 3D data. The ores consist of a copper-rich Iss composed of tiny lamellar intergrowths of cubanite and chalcopyrite solid solutions, which form up to 4-mm distinct globules surrounded by an Iss-Mss matrix. Our X-ray computed micro tomography results provide 3D textural evidence of a possible natural sulfide-sulfide liquid immiscibility between Cu-rich and Cu-poor sulfide liquids. The platinum-group minerals (PGM) distribution shows that 20.6 Vol.-% of all PGMs occur in the Iss-Mss matrix and 79.4 Vol.-% in the Iss globules. We believe that this distributional behavior is due to the fact that the platinum group elements (PGE) cannot be dissolved in Iss, which led to the formation of the large PGM grains, which are up to 120 μm on their longest axis. The initial enrichment of Iss with PGEs was controlled by differences in the partition coefficients of platinum and palladium Cu-poor and Cu-rich liquids.