The Phase System Fe-Ir-S at 1100, 1000 and 800°C

E. Makovicky1 and S. Karup-Møller2
1 Department of Mineralogy, The Geological Central Institute, University of Copenhagen, Østervoldgade 10, DK 1350 Copenhagen K, Denmark
2 Department of Geology and Geotechnical Engineering, The Technical University of Denmark, DK 2800 Lyngby, Denmark

Abstract: Phase relations in the dry condensed Fe-Ir-S system were determined at 1100, 1000 and 800°C. Orientational runs were performed at 500°C. Between 1100 and 800°C, the system comprises five sulphides and an uninterrupted field of γ(Fe,Ir). Fe2−xS dissolves 5.8 at.% Ir at 1100°C, 3.4 at.% Ir at 1000°C and 1.0 at.% Ir at 800°C. The solubility of Fe in Ir2S3, IrS2 and IrS−3 increases with decreasing temperature, reaching 2.5 at.% in the latter two sulphides at 800°C. Thiospinel ‘FeIr2S4’ is non-stoichiometric, from Fe22.3Ir19.8S58.0 to Fe18.9Ir23.1S58.0, depending on as and aFe i.e. on a phase association. Thiospinel is absent at 800 and 500°C.

Keywords: platinum group elements • iridium • phase system iron-iridium-sulphur

Mineralogical Magazine; June 1999 v. 63; no. 3; p. 379-385; DOI: 10.1180/002646199548600
© 1999, The Mineralogical Society
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