Photo: VCG

Chinese scientists have, for the first time, captured at the nanoscale the dynamic process by which natural gold nanoparticles form on the surface of pyrite, and proposed a new mechanism in which pyrite induces gold precipitation, state broadcaster CCTV News reported on Wednesday.

The CCTV News cited the Guangzhou Institute of Geochemistry under the Chinese Academy of Sciences as saying that a research team recently used in-situ liquid-phase transmission electron microscopy to discover a special "dense liquid layer" at the pyrite-water interface. 

Acting like a "nano-factory," this layer can efficiently catalyze the nucleation, growth and enrichment of gold even in fluids with extremely low gold concentrations—on the order of parts per billion—offering a new perspective on the genesis of gold deposits. The findings were published on January 20 in the international academic journal Proceedings of the National Academy of Sciences (PNAS).

Pyrite-induced gold precipitation is a key step in the formation of high-grade gold deposits, yet its interfacial dynamic mechanism has long remained unclear. Previous studies mainly relied on post-reaction, offline analyses, making it difficult to capture the instantaneous processes and mechanisms of gold deposition. 

In this study, after excluding the effects of dissolved oxygen and electron-beam interference, the team employed in-situ liquid-phase transmission electron microscopy along with other multi-scale techniques to observe in real time the reaction between pyrite and gold-bearing solutions at ultra-low concentrations.

The results showed that about 13 minutes after contact, a stable "dense liquid layer" formed around the pyrite. Roughly 20 minutes later, gold nanoparticles began to appear within this layer and, over time, increased in both number and size. This discovery provides critical evidence for understanding how gold forms on pyrite surfaces, according to CCTV News.

The study challenges the traditional view that gold mainly originates from deep hydrothermal fluids and opens a new pathway for understanding nanoparticle-driven mineralization processes in nature. From an applied perspective, the mechanism also offers guidance for interfacial regulation in green gold-leaching technologies, the report said.

Global Times