ABSTRACT

Sulfur isotope fractionation in ZnS-HS^- and PbS-HS^- systems has been studied experimentally in the temperature range from 50 to 340°C. Sulfur isotopic exchange between sulfide minerals and HS^- ions was found to be unexpectedly fast. In the ZnS-HS^- system several ten hours are enough to attain isotopic equilibrium in the temperature range from 50 to 200°C. Temperature dependence of equilibrium fractionation was estimated as follows: In α_{sphalerite-HS^-}= 111T^-2 + 0.00136 In α_galena-HS^-=-782 T^-2 + 0.00170 From these equations the temperature dependence of sphalerite-galena fractionation is In α_{sphalerite-galena}=891 T^-2-0.00057.