Epigenetic Alteration of Cupreous Gold in the Au–Ag–Cu–Pd Exsolution Texture

Abstract

The exsolution texture of the Au–Ag–Cu–Pt solid solution is represented by numerous lamellae of cupreous gold in the Ag–Au–Pd matrix. On average, the lamellae contain Au–87.1 wt %, Cu–10.3 wt %, Pd–1.8 wt %, and Ag–1.1 wt %, which corresponds to the Au3Cu mineral phase. We revealed for the first time that cupreous gold lamellae were selectively replaced by high-grade gold (98 wt % Au), with a very precise inheritance of the exsolution texture. The substitution occurred due to the impact of epigenetic solutions on native gold with the removal of relatively mobile components.