Thermodynamic Modelling Of Physicochemical Conditions Of Gold Ore Genesis

Abstract

The relevance of this research is dictated by the need of geologists, ore enrichment specialist,
metallurgists and mining engineers who are involved into prospecting, extracting and processing of gold,
and, therefore, should know the conditions of the high-grade ore genesis, in order to reduce losses during
mining, extraction or benefaction. The purpose of this study is thermodynamic simulation modelling of
physicochemical conditions of the high-grade gold ore formation in the hydrothermally altered host rocks at
different levels of erosion. In modelling, equilibrium mineral assemblages in the ores were obtained by
minimizing the Gibbs free energy of chemical processes. The thermodynamic modelling of gold deposition
was based on mineralogical-petrographic volumetric mapping and quantitative phase analysis of the ore and
host rock samples.
The high-grade gold ore genesis is associated with volcanic apparatus and occurs at 10-12 km depth,
at a temperature of 600-500°C and pressure of 500-300 MPa in hydromica-quartz and dolomite-quartz-illite
metasomatites. The high temperature of gold formation can be confirmed by the presence of sanidine, a hightemperature monoclinic polymorph of potassium feldspar that remains stable up to 900°C; while the depth
of formation can be confirmed by the gold content of 78 g/t at more than 9 km depth in the Kola Superdeep
Borehole.
This paper can be of interest for geologists, mineralogists, petrologists, mining engineers and
metallurgists.