The sulphur-poor portions of the dry condensed Cu-Fe-Pd-S system were studied at 1000°C, 900°C and 725°C by synthesis in evacuated silicate glass tubes, along with textural observations and electron microprobe analyses of equilibrated reaction products. Sulphide melt coexists with Cu-Fe-Pd alloys, bornite, Fe1-xS and iss (intermediate solid solution, Cabri, 1973) and Pd4S. Compositional data were obtained for the associations bornite-alloy-melt, pyrrhotite-alloy-melt and for immiscible Cu-rich sulphide melts. Partition coefficients for all three metals were derived for the association alloy-melt. Formation of the two new Cu-Pd alloy minerals, skaergaardite and nielsenite, is discussed in terms of the present findings.
