DETERMINATION OF BINDING FORMS OF GOLD IN PYRITE BY MEANS OF STATISTICAL ANALYSIS

Abstract

Experiments show that the concentration of lattice gold can be estimated against the bulk Au content dominated by sorption gold using extrapolation of the concentration of uniformly distributed Au vs. mean specific surface of crystal dependence onto the region where the effect of surface is negligible. The optimum mean specific surface of gold is 6 cm2/g. This approach is applicable to natural minerals as well. Comparison of synthetic and natural pyrite from Au-Ag deposits and occurrences in northeastern Russia shows that almost all uniformly distributed (invisible) gold in pyrite is due rather to sorption than to incorporation of Au into the mineral structure, while both ways of incorporation occur by the same mechanism related to reactivity of defect sites on crystal surface. High concentrations of invisible gold in pyrite are due to sorption on crystal surfaces of AuD particles and, possibly, more complex metastable Au-bearing phases produced by exsolution of intermediate compounds and complexes of Au and GGE (primarily, As).