STOICHIOMETRY OF FAHLORE COMPOSITIONS

Abstract

Precision analyses of various natural fahlores, analyses of fahlores synthesized in the hydrothermal systems Cu-Sb-S at 200°C and Cu-Fe-Sb-S, Cu-Fe-As-S and Cu(Ag)-Cd(Fe, Zn)-Sb(As)-S at 200° to 550°C, and investigation of the electronic structure and electrical properties of these minerals unequivocally indicate that they are stoichiometric within the limits of microprobe analytical error. Fahlores are components of late hydrothermal mineral associations, formed at temperatures of about 200° to 250°C. Thus, we can understand why there is an apparent fit between compositions of natural fahlores and minerals synthesized at relatively low temperatures: the compositions of both are stoichiometric.