New Silver‑Rich Mineral Fengruiite Discovered in Chinese Deposit

A team of mineralogists announced the discovery of Fengruiite, a new silver‑sulphide salt containing antimony and tellurium, found in the Haopinggou Ag–Pb–Zn–Au deposit in eastern Qinling, China. The study appears in volume 38 of European Journal of Mineralogy (2026) and details the mineral’s composition as \(\). The authors—Yongfei Tian, Guowu Li, Ningyue Sun, Min Liu, Jingwen Mao, Yunpeng Dong, Peng Liu, Wei Jian, Wei Yao, Xiuquan Wang, and Huishou Ye—used microscopy, chemical analysis, and crystal‑structure tests to confirm its novelty ¹.

Fengruiite is notable for its tellurium‑rich structure that traps and concentrates silver during ore formation. In hot mineral‑forming fluids, tellurium atoms bind with silver, creating a stable lattice that sequesters the metal until it crystallizes. This mechanism offers fresh insight into how silver‑rich deposits develop in hydrothermal systems ¹.

The research also highlights copper within the mineral: the formula includes \(Ag_9CuS_2Te_2\), indicating that copper co‑precipitates alongside silver and tellurium. Such associations may explain why certain ore bodies exhibit high grades of multiple base metals simultaneously.

Expert commentary underscores that identifying new species like Fengruiite helps refine exploration models. “This newly discovered silver-rich mineral has a unique tellurium-rich structure that helped trap and concentrate silver in hot mineral-forming fluids,” notes the lead researcher, pointing out that tellurium played a significant role in how silver was stored in nature ¹.

The paper documents the mineral’s crystal lattice: layers of six‑fold coordinated silver atoms decorated with antimony groups and connected through sulfur bonds. This arrangement is unprecedented among sulfosalts, suggesting a distinct crystallization pathway influenced by local fluid chemistry. The authors emphasize that such structural uniqueness underlines the importance of detailed laboratory work when surveying complex ore bodies.

In summary, Fengruiite adds another rare member to the family of Ag–Sb–Te minerals and demonstrates a tangible link between tellurium chemistry and silver enrichment.