Geochemical evidence suggests that arsenic is a crucial factor reinforcing gold mineralization in pyrite. The systematic presence of Au-bearing arsenian pyrite in hydrothermal systems suggests a coupled Au–As geochemical behavior in various physico-chemical conditions. However, there is a lack of understanding of elemental interactions at the atomic scale during gold mineralization, leaving unresolved which specific structural configurations host Au–As interactions and whether other trace elements can exert effects similar to arsenic. In this study, we use ab initio simulations to quantitatively evaluate interactions between elemental impurities in pyrite, specifically focusing on the gold-arsenic relation. We consider a wide range of chemical and structural substitutions, for which we monitor the structural distortions they induce and calculate their formation energies. We show that individual incorporations of impurity atoms are prohibitive. But joint substitutions better accommodate the induced stress, decrease energy barriers, and thereby facilitate gold incorporation. Among various trace elements, arsenic substitution for sulfur is the most favorable for gold incorporation, due to the formation of [AuAs_nS_6-n] coordination octahedra, with Au substituting Fe. The presence of As effectively alleviates the lattice stress associated with Au substitution, and restricts it within the local coordination polyhedron, thereby facilitating the large-scale, long-term preservation of Au in pyrite. Our study provides a novel insight into co-evolutionary processes in ore deposits, with a focus on pyrite-hosted Au deposits.

Article link: https://doi.org/10.1016/j.gca.2026.03.055