Direct conversion of sulphide and sulphate minerals to SO2 for isotope analyses

Abstract

Sulphide and sulphate minerals mixed with V205 and SiO2, were heated in a vacuum at 950°C for 15 minutes, The evolved SO3was converted to SO2by reaction with metallic Cu for sulphur isotope determinations. This technique yields SO2of consistent oxygen isotope composition regardless of whether sulphide or sulphate is converted. The reproducibilities of sulphur conversion and S34S values were 98 ±5% and ±0,2%, respectively. The technique is particularly suitable for small samples. Successful isotope determinations have been obtained with natural samples containing less than I mg S. In some cases, variations in 534S of 2% have been found for single grains analysed from a small specimen. © 1986, GEOCHEMICAL SOCIETY OF JAPAN. All rights reserved.