Thermodynamic Mixing Properties of Pyrrhotine, Fe1−XS

Roger Powell
Department of Earth Sciences, University of Leeds, Leeds LS2 9JT

Abstract: Published data from pyrrhotine-vapour equilibrium experiments are used to make inferences concerning the high-temperature thermodynamic mixing properties of pyrrhotine. Darken's quadratic formalism provides the justification for plotting activity of sulphur data against (1−X)2, where X is used in Fe1−XS to express the composition of non-stoichiometric pyrrhotine. Such plots show that the thermodynamic behaviour of pyrrhotine appears to be different on either side of X = 0.125, the Fe7S8 composition.

Mineralogical Magazine; December 1983 v. 47; no. 345; p. 437-440; DOI: 10.1180/minmag.1983.047.345.04
© 1983, The Mineralogical Society
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