Thermodynamic modeling of native formation of Au–Ag–Cu–Hg solid solutions

Abstract

It is difficult to interpret the significance of some types of gold alloys without thermodynamic data describing the Au–Ag–Cu–Hg systems. Literature data on the content of copper and mercury in native gold and silver and that of silver and gold in native copper and mercury from gold deposits of different genesis were collected and analyzed. Activity coefficients of the solid solutions in Au–Ag–Cu–Hg quaternary system were estimated. The corresponding calculation module prepared for a “Selektor-C” software package allows calculation of the composition of quaternary solid solutions depending on the change in T,P,X-parameters. Ore formation scenarios were modeled for two objects: i) “hydrothermal” – on the example of formation of quaternary solid solutions in hydrothermal conditions at the Aitik Au–Ag–Cu porphyry deposit (Sweden); ii) “hydrothermal-hypergene” – on the example of formation of Au–Cu intermetallics at the Wheaton Creek placer deposit (Canada). The approach described in our work can be used as an additional tool for the analysis of the genesis of gold deposits and estimation of formation conditions of natural solid solutions of noble metals that are in many cases the main carriers of ore components.