Analysis of oxidized layers on pyrite surfaces by X-ray emission spectroscopy and cyclic voltammetry

X-Ray emission spectroscopic analysis of the surface of the iron sulphide mineral, pyrite, has demonstrated the presence of an oxygen- containing layer. Differences between the quantity of oxygen detected after grinding the pyrite on 600 grade silicon carbide paper and polishing it to the 10 μm or 0.25 μm diamond stage are considered to be due to differences in surface roughness. Triangular potential sweep voltammograms display current peaks which have been identified with the oxidation and reduction of the oxide layer between iron(II) and iron(III) valence states. The quantities of oxide on the surface determined from the charge passed on a potential sweep correlate with the X-ray emission measurements for the three surface preparations.