X-ray photoelectron spectroscopy of oxidized pyrrhotite surfaces

Abstract

The oxidation of fracture surfaces of a pyrrhotite mineral of composition Fe_0.89S at ambient conditions in air has been studied by X-ray photoelectron spectroscopy (XPS). Fe(2p) and Fe(3p) spectra indicated that iron had diffused from the outermost layers of the mineral lattice to form a hydrated iron(III) oxide or hydro-oxide. The corresponding S(2p) spectrum exhibited a shifted component at a binding energy increasing with time of exposure. It is considered that this component arises from the formation of iron-deficient sulfides with the iron content decreasing with increasing oxidation time.