Mineralogy of Zn–Hg–S and Hg–Se–S Series Minerals in Carbonate-Hosted Mercury Deposits in Western Hunan, South China

Abstract

Among the Zn-Hg-S and Hg-Se-S series minerals, Hg-bearing sphalerite and metacinnabar are uncommon in ore deposits, but they are useful indicators of temporal variation of ore forming fluids, as well as presenting metallurgical implications for Hg-bearing deposits. To understand the Hg-Zn-Se mineralization system of the Tongren-Fenghuang Hg Belt (TFHB), the Zn-Hg-S and Hg-Se-S series minerals of the Chashula Hg-Zn and Dongping Hg-Ag-Se carbonate-hosted deposits were studied by microscopic observation, electron-probe microanalysis, and X-ray diffraction analysis. Observations show that the Chashula and Dongping deposits experienced two stages of mineralization (Stages 1 and 2). The pyrite, sphalerite I (Hg-poor sphalerite), and quartz formed in Stage 1, while the Zn-bearing cinnabar, sphalerite II (Hg-bearing sphalerite), cinnabar, selenium metacinnabar, and Ag minerals formed in Stage 2. The Hg-bearing sphalerite, containing 13.36-22.26 wt % Hg (average 18.73 wt % Hg), replaces sphalerite I (0.00-1.31 wt % Hg). The Hg-bearing sphalerite of the Dongping Hg-Ag-Se deposit contains lower Hg (10.12-14.67 wt % Hg) than that of the Chashula deposit. The unit cell a of the Hg-bearing sphalerite gradually increases with increasing Hg content. The texture of the Zn-bearing cinnabar shows it is not stable and easily breaks down to Hg-bearing sphalerite and cinnabar through the chemical reaction: (Hg,Zn)S → (Zn,Hg)S + HgS. Selenium metacinnabar intergrowths with tetrahedrite and miargyrite were found only in the Dongping deposit. The selenium metacinnabar contains 76.57-83.97 wt % Hg, and extensive isomorphic substitution of .21 wt % Se, 4.14-10.32 wt % S). Based on our mineralogical studies, the Zn, Hg, Hg-Zn, and Hg-Se mineralization styles in the TFHB are interpreted as the product of different stages in the mineralization process.

A Paleozoic mercury mineralisation event in South China: In situ U-Pb dating and chemical compositions of calcite from the Jianyan Hg deposit

“…In the south-eastern Yangtze Block, carbonate-hosted Hg deposits are Hg-only deposits or related to Pb-Zn mineralisation, with Zn ore zones being better developed close to mineralisation along faults, such as the Chashula, Chatian, and Dadongla Hg-Pb-Zn deposits (Figure 1; Liu et al, 2017). These deposits may also contain Ba-F mineralisation and are generally hosted in Cambrian to Ordovician carbonate rocks.…”

Ge-Hg-Rich Sphalerite and Pb, Sb, As, Hg, and Ag Sulfide Assemblages in Mud Volcanoes of Sakhalin Island, Russia: An Insight into Possible Origin

“…The instrument was tuned to ThO/Th ratios of <0.3% and U/Th ratios of ~100%, doubly charged cations were tuned to <0.4% using SRM NIST610, and SRM NIST612 as unknown. The measured isotopes were: 24 Mg, 27 Al, 28 Si, 33 S, 34 S, 39 K, 43 Ca, 44 Ca, 51 V, 52 Cr, 55 Mn, 56 Fe, 57 Fe, 59 Co, 60 Ni, 65 Cu, 66 Zn, 70 Ge, 71 Ga, 75 As, 82 Se, 95 Mo, 107 Ag, 111 Cd, 115 In, 121 Sb, 125 Te, 197 Au, 202 Hg, 205 Tl, 208 Pb, 209 Bi and 238 U.…”

“…Although sphalerite with medium or high Hg contents and Zn-bearing metacinnabar in complex sulfide deposits are often found worldwide and have been largely studied [1,3,4,[79][80][81][82], some issues remain unresolved, such as Hg incorporation into the ZnS structure, Hg valence, or ranges of (Zn,Hg)S cub and (Hg,Zn)S cub solid solutions [1,3,83].…”

“…[1], China [8], Germany [16] and Iran [105]. 2 = Hg contents in sphalerites (EDS-WDS data) from different Hg deposits of Canada [1], Russia, Ukraine, Mongolia, Kyrgyzstan, Uzbekistan [3], and China [82] We undertook special efforts to check the homogeneity of the Sakhalin MV sphalerite grains with abnormal concentrations of Ge and Hg (Figure 22) by means of XRD analysis and Raman spectroscopy, but found no inclusions of Hg or Ge phases, which supported the isomorphic incorporation of both Hg and Ge into the sphalerite structure. Compared to the sphalerites of Vein-type and MVT deposits, those from Sakhalin have two orders of magnitude greater contents of Ge (3008-3408 ppm) and one or two orders of magnitude greater Hg contents (83.2 ppm to 27 wt%), even in low-and medium-Hg varieties [2,3,82].…”