COMPOSITION AND PHASE RATIOS OF TENNANTITE IN THE SYSTEM CU-FE-AS AT 500°C

Abstract

No data is available on the composition and phase ratios of tennantite in the system Cu-Fe-As-S. Consequently, we made an experimental study of this system. The results of this work prove that tennantite is a terminal (bounded) solid solution (TSS) with a cone-shaped homogeneity field. The composition in the base of this cone varies within the range from Cu12,3As4,05S13 to Cu13,32As4,02S13, which is somewhat narrower than the composition range of tennantite in the same system, earlier established by S. Maske and B.J. Skinner. Experimental data indicate that the composition of tennantite in the system Cu-Fe-As-S varies in many respects just like the composition of the isostructural antimony end member, tetrahedrite, in the system Cu-Fe-Sb-S, whose homogeneity range also becomes narrower as the iron content rises.