Experimental Study on Gold Dissolution from Hosting Minerals of the Hadamengou Gold Deposit and the Implications

AbstractThe Hadamengou gold deposit is located in western part of the northern margin of the North China craton. It is a hydrothermal deposit related to alkaline magmatism. Dissolution of Au, Fe from pyrite and iron oxide (including magnetite and hematite) individual minerals in the three main types of ore shows: in iron oxides (magnetite and hematite), Au and Fe were dissolved simultaneously and their solubilities are positively correlated, which means Au is mainly chemical‐bonded (lattice gold) and/or colloidal‐adsorbed in iron oxides; while in pyrite, on the contrary, Au dissolution obviously lags behind Fe and the solubility of Au shows negative relationship with that of Fe, which indicates Au is mainly hosted as grains of elemental gold (or native gold) within pyrite. Previous studies revealed that the Hadamengou gold deposit is characterized by intensive K‐feldspathization and holds high content of iron oxides occasionally replaced by sulfides, which was caused by oxidizing K‐enriched alkaline fluids under a stretching geodynamic setting. These geological features, together with the high Au‐content in iron oxides, comparable with that of the Olympic Dam deposit in South Australia, suggest that this deposit is the first example of iron oxide‐type gold deposits in China.