Eliopoulosite, V7S8, A New Sulfide from the Podiform Chromitite of the Othrys Ophiolite, Greece

Minerals

Giorgio Garuti¹  Federica Zaccarini¹  Chris Stanley²  Paola Bonazzi³  Luca Bindi³  Basilios Tsikouras⁴  Tassos Grammatikopoulos⁵ 

[1] Department of Applied Geological Sciences and Geophysics, University of Leoben, A-8700 Leoben, Austria;Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK;Dipartimento di Scienze della Terra, Università degli Studi di Firenze, I-50121 Florence, Italy;Faculty of Science, Physical and Geological Sciences, Universiti Brunei Darussalam, BE 1410 Gadong, Brunei Darussalam;SGS Canada Inc., 185 Concession Street, PO 4300, Lakefield, Ontario K0L 2H0, Canada;

关键词: eliopoulosite;    sulfide;    chromitite;    agios stefanos mine;    othrys;    ophiolite;    greece;   

DOI  :  10.3390/min10030245

来源: DOAJ

【 摘 要 】

The new mineral species, eliopoulosite, V₇S₈, was discovered in the abandoned chromium mine of Agios Stefanos of the Othrys ophiolite, located in central Greece. The investigated samples consist of massive chromitite hosted in a strongly altered mantle tectonite, and are associated with nickelphosphide, awaruite, tsikourasite, and grammatikopoulosite. Eliopoulosite is brittle and has a metallic luster. In plane-reflected polarized light, it is grayish-brown and shows no internal reflections, bireflectance, and pleochroism. It is weakly anisotropic, with colors varying from light to dark greenish. Reflectance values of mineral in air (R_o, R_e’ in %) are: 34.8−35.7 at 470 nm, 38−39 at 546 nm, 40−41.3 at 589 nm, and 42.5−44.2 at 650 nm. Electron-microprobe analyses yielded a mean composition (wt.%) of: S 41.78, V 54.11, Ni 1.71, Fe 1.1, Co 0.67, and Mo 0.66, totali 100.03. On the basis of Σ_atoms = 15 apfu and taking into account the structural data, the empirical formula of eliopoulosite is (V_6.55Ni_0.19Fe_0.12Co_0.07Mo_0.04)_{Σ = 6.97}S_8.03. The simplified formula is (V, Ni, Fe)₇S₈ and the ideal formula is V₇S₈, which corresponds to V 58.16%, S 41.84%, total 100 wt.%. The density, based on the empirical formula and unit-cell volume refined form single-crystal structure XRD data, is 4.545 g·cm⁻³. The mineral is trigonal, space group P3₂21, with a = 6.689(3) Å, c = 17.403(6) Å, V = 674.4(5) ų, Z = 3, and exhibits a twelve-fold superstructure (2a × 2a × 3c) of the NiAs-type subcell with V-atoms octahedrally coordinated by S atoms. The distribution of vacancies is discussed in relation to other pyrrhotite-like compounds. The mineral name is for Dr. Demetrios Eliopoulos (1947−2019), a geoscientist at the Institute of Geology and Mineral Exploration (IGME) of Greece and his widow, Prof. Maria Eliopoulos (nee Economou, 1947), University of Athens, Greece, for their contributions to the knowledge of ore deposits of Greece and to the mineralogical, petrographic, and geochemical studies of ophiolites, including the Othrys complex. The mineral and its name have been approved by the Commission of New Minerals, Nomenclature, and Classification of the International Mineralogical Association (No. 2019-96).

【 授权许可】

Unknown