GUANGZHOU: Chinese scientists have uncovered how gold nanoparticles dynamically form on pyrite surfaces at the nanoscale, offering fresh insight into the origins of gold deposits. The findings were published on Thursday in the journal “Proceedings of the National Academy of Sciences” (PNAS).
According to the study, a distinctive “dense liquid layer” develops at the interface between pyrite and water, functioning like a microscopic factory that facilitates the nucleation, growth, and accumulation of gold. Remarkably, this process occurs even when gold concentrations in the surrounding fluid are extremely low—around 10 parts per billion.
The discovery provides a new framework for understanding how gold ores can form from highly diluted gold-bearing solutions. While pyrite-induced gold precipitation is known to be a key step in the development of high-grade gold deposits, the underlying interfacial dynamics had long remained poorly understood.
Previous research mainly relied on post-reaction analysis, making it difficult to observe gold formation as it happened. In the latest study, a research team led by the Guangzhou Institute of Geochemistry under the Chinese Academy of Sciences succeeded in monitoring, in real time, the interaction between pyrite and low-concentration gold-bearing fluids.
The observations showed that around 13 minutes after contact, a dense liquid layer emerged around the pyrite surface. Roughly 20 minutes later, gold nanoparticles began to appear within this layer, gradually increasing in both number and size over time.
These real-time observations provide crucial evidence explaining how gold accumulates at the pyrite–water interface. The findings also challenge the long-standing belief that gold mainly originates from deep hydrothermal fluids, and they open up new possibilities for understanding nanoparticle-driven mineralization processes in natural environments.
