The oxidation states of copper and iron in mineral sulfides, and the oxides formed on initial exposure of chalcopyrite and bornite to air

Electronic environments in carrollite, CuCo2S4, determined by soft X-ray photoelectron and absorption spectroscopy

“…The presence of a Cu-only sulfide phase might not be as easily detectable by XPS as a Cu-Fe sulfide phase. Nevertheless, the presence at the fracture surfaces investigated of neither CuS, which has its L 3 peak at 932.2 ± 0.2 eV (Goh et al, 2006), nor CuS 2 , which is expected to have its L 3 peak near 932.6 eV (Mosselmans et al, 1995), was evident from the characteristics of the S 2p photoelectron spectrum determined at a photon energy of 800 eV. Moreover, the intensity ratio of the doublet components in the principal Cu L 3 peak was the same for different fracture surfaces and different regions of the same fracture surface.…”

A hybrid-exchange density functional study of the bonding and electronic structure in bulk CuFeS2

“…The oxidation state of Cu 2 S has been established as (Cu + ) 2 S 2− , from the analysis of near-edge X-ray adsorption fine structure (NEXAFS) spectra obtained by Goh et al 41 . Greigite, which has a spinel structure and a cubic unit cell, is believed to form from the oxidation of two thirds of Fe 2+ cations in mackinawite (Fe 2+ S 2− ), in addition to rearrangement of the cubic S anion sublattice 42 .…”

Anoxic versus oxic sample pretreatment: Effects on the speciation of sulfur and iron in well-aerated and wetland soils as assessed by X-ray absorption near-edge spectroscopy (XANES)

“…Together with the dominance of Fe oxyhydroxides in Histosol 2, which was observed in our Fe K-edge XANES study (Table 5), but also by Na dithionite extraction , this finding emphasizes the lability of sulfide-bound Fe(II) against oxygenation, may it appear during sampling or during changes in soil hydrological conditions. Several studies showed that Fe 2+ in Fe sulfide minerals is rapidly oxidized in contact with O 2 (Buckley and Woods, 1985;1987;Simpson et al, 1998;Ward et al, 2004;Goh et al, 2006;Paul et al, 2006): the reaction starts with the formation of surface Fe(III) oxyhydroxides within minutes after oxygenation (Goh et al, 2006); Fe monosulfides oxidize more rapidly than pyrite Woods, 1985, 1987;Goh et al, 2006) or heavy metal sulfides (Simpson et al, 1998).…”

“…1). These forms are conventionally assigned to inorganic sulfides, such as FeS, pyrrhotite, or pyrite (see compilation in Prietzel et al, 2003;Goh et al, 2006; Table 2). In the mineral soil horizons, the decrease of peaks at energies<2472 eV was associated with an increase of the peak at 2482.5 eV representing oxidized S(VI+), which can be easily explained by oxidation of sulfide to sulfate (Bloomfield, 1972;Engler and Patrick, 1973;Wieder et al, 1985;Maher et al, 2004;Ward et al, 2004;Bottrell et al, 2007).…”