Sulfur radical species form gold deposits on Earth

Gold resources on Earth result from an exceptional concentration phenomenon yielding metal contents in ore a thousand to a million times higher than those in common rocks. We show that this process is controlled by sulfur radical ions (S₃^-), which strongly bind Au in aqueous solution at elevated temperatures and pressures and allow very efficient extraction, transport, and deposition of gold by geological fluids. Thus, the most inert metal of the periodic table may be very mobile, which explains key features of known gold deposits and offers new possibilities for resource prospecting. Furthermore, the high capacity of the radical ions to solubilize gold may be used for its selective extraction from ores and hydrothermal synthesis of Au-based nanomaterials.