Chemical mapping of elemental sulfur on pyrite and arsenopyrite surfaces using near-infrared Raman imaging microscopy

Near-infrared Raman imaging microscopy (NIRIM) was used to produce chemical images of the distribution of elemental sulfur on oxidized pyrite and arse nopyrite surfaces. Analysis using Savitsky-Golay filtering permits an unamb iguous identification of surface products even in the presence of broad bac kground signals. Rather than forming a continuous, passivating layer at the mineral surface, the NIRIM images reveal that elemental sulfur forms in is olated patches on the order of tens of microns in diameter. The potential i mplications of this strongly heterogeneous distribution of chemical product s for geochemical modeling of acid mine drainage (AMD) are discussed. (C) 2 001 Elsevier Science B.V. All rights reserved.