Chemical Forms of Mercury in Pyrite: Implications for Predicting Mercury Releases in Acid Mine Drainage Settings

Research reveals that mercury (Hg) within pyrite—a common metal sulfide—exists in distinct chemical forms depending on its geological origin, significantly influencing mercury release dynamics in acid mine drainage. Using high energy-resolution X-ray absorption spectroscopy, scientists identified that Hg in coal-derived pyrite and sedimentary rocks occupies different structural sites compared to hydrothermal ore deposits. Notably, epigenetic pyrite from Carlin-type gold deposits contains up to 55% of its total Hg as metacinnabar nanoparticles, while Idrija-type mercury deposits feature a mix of divalent, substitutional, and elemental (liquid) Hg forms. These findings provide critical insights into predicting environmental pathways of mercury released during oxidative dissolution of pyrite in mining-impacted watersheds, offering potential for targeted control strategies to mitigate mercury contamination.

Manceau, A., Merkulova, M., Murdzek, M., Batanova, V., Baran, R., Glatzel, P., Saikia, B. K., Paktunc, D., & Lefticariu, L. (2018). Chemical Forms of Mercury in Pyrite: Implications for Predicting Mercury Releases in Acid Mine Drainage Settings. Environmental Science & Technology, 52(18), 10286–10296. https://doi.org/10.1021/acs.est.8b02027