Original paper

New phase relations in the Cu-Fe-S system at 800C; constraint of fractional crystallization of a sulfide liquid

Tsujimura, Tomoyuki; Kitakaze, Arashi


Phase equilibrium in the Cu–Fe–S system has been investigated for over 100 samples by the sealed silica tube method at 800°C. Bornite shows solid solutions ranging from (Cu4.70 Fe1.30)6.00S4.00 to (Cu7.43Fe0.00)7.43S4.00, and those of pyrrhotite ranges from (Cu0.04Fe1.01)1.05S1.00 to (Cu0.00Fe1.00)1.00S1.00. The intermediate solid solution (iss) and the sulfide liquid exist in the central part of this system. The most important difference between the phase diagram obtained in this study with that reported by Kullerud et al. (1969) is that the sulfide liquid is between bornite and pyrrhotite, and that the tie-lines between bornite and iss and between bornite and pyrrhotite are unstable. The new phase diagram of this system at 800°C is reported.


cu-fe-sborniteisspyrrhotitesulfide liquid