A team from the Chinese Academy of Sciences and the Guangzhou Institute of Geochemistry has recorded the full process of gold forming on the surface of pyrite in aqueous solution. The experiment suggests that under mild, near-surface conditions, pyrite can help reduce gold ions into metallic gold, a finding that has drawn attention from the mining sector and commodity markets.
A dense liquid layer appeared at minute 13, nucleation started at minute 20
Researchers used in-situ liquid-phase transmission electron microscopy and placed pyrite crystals together with a gold-bearing solution at a concentration of just 10 ppb inside a sealed observation cell. The camera captured a dense liquid layer forming on the crystal surface at minute 13. By minute 20, nanoscale gold particles began to nucleate and cluster within that layer. The result offers direct visual evidence that gold formation does not always require high-temperature, high-pressure settings.
Oxygen consumption by pyrite created the conditions for reduction
According to the report, the key chemical process begins when dissolving pyrite consumes large amounts of oxygen molecules in the solution, causing local oxygen fugacity to drop quickly. In that low-oxygen microenvironment, gold ions gain electrons and precipitate as metallic gold. This runs against the long-held view that gold deposits must come from deep crustal hydrothermal systems. It also helps explain why fine-grained gold is often found together with pyrite in riverbeds and weathered near-surface zones.
Cleaner extraction and tailings recovery gain a fresh research basis
Gold extraction has long relied on cyanide leaching, a process tied to high energy use and toxicity concerns, and one that often faces scrutiny from ESG-focused investors. The newly observed interfacial chemical reaction gives researchers a theoretical basis for designing low-temperature, lower-toxicity extraction methods. If the microenvironment of the dense liquid layer can be reproduced artificially, low-grade ores and mine tailings may one day yield precious metals without the use of highly toxic reagents.
Natural-like concentrations were tested, but industrial scaling remains open
The concentration used in the experiment, 10 ppb, is already close to conditions found in natural waters. Industrial deployment is still unresolved. Reaction speed, control of the liquid layer, and overall cost remain practical barriers, and the research team has not announced a production-scale plan. Even so, the work establishes that gold can form in shallow, low-temperature environments under observable laboratory conditions.