Characteristics and Formation Conditions of Se-Bearing Metacinnabar in the Wanshan Mercury Ore Field, Eastern Guizhou

Cinnabar (α-HgS) is the most common sulfide of mercury while metacinnabar (β-HgS), a high-temperature homogeneous polymorph sulfide, relatively rare, and α phase cinnabar transforms to β at 344 °C. Meanwhile, there complete isomorphic series between HgS HgSe, occurrence Se-bearing great significance for exploration selenium resources. We studied through microscopic observation, electron-probe microanalysis, X-ray diffraction field emission scanning electronic microscopy (FESEM) Wanshan ore southeastern Yangtze Block. These analyses, combined with physicochemical diagrams, constrained textural chemical evolution during formation process metacinnabar. was found in altered carbonatite, intergrown cinnabar, sphalerite, pyrite, realgar quartz. The contains 77.66–84.01 wt.% Hg, 0.18–1.17 Zn extensive substitution Se S (2.79–14.77 Se, 6.15–11.82 S). presence impurity elements (e.g., Se) considered be key factor expanding stable range generated by transformation characterized inclusions Hg-bearing sphalerite pores, which indicate that this carried out coupled dissolution–reprecipitation (CDR) reaction. temperature higher than according relations sulfides selenides, we propose logfS2(g) ore-forming fluids within −15.663 −13.141, logfSe2 < logfS2–3.994 (150 °C).