Influence of the Phase Composition of Pyrrhotites on Gold Content in Rocks

Abstract

On the basis of comprehensive analysis of the crystal structure, chemical and phase composition of natural pyrrhotites of the “Blagodatny” mine (Krasnoyarsk region), an analytical expression for calculating the concentration of point defects in nonstoichiometric minerals is obtained. Calculation of concentration of point defects in the crystal structure of natural pyrrhotites of various chemical compounds is made and compared with the gold content in samples. Concentration of point defects is calculated separately for the inclusion of defects (Co, Ni, Cu, Zn, Sb, etc.), and cation vacancies in the crystal structure. As a result of theoretical calculations and the analysis of X-ray spectra and the chemical composition, the dependence of the concentration of point defects and their ordering in the crystal structure on the gold content in the rock is established. The maximum content of gold corresponds to pyrrhotites in which vacancies are completely ordered in even (odd) basic planes of structure of type NiAs. The chemical formula for content representation of the nonstoichiometric minerals containing crystal structure of atoms, distinct from atoms of a forming matrix, is offered.