TY - JOUR

T1 - Eliopoulosite, V7S8, A New Sulfide from the Podiform Chromitite of the Othrys Ophiolite, Greece

AU - Bindi, Luca

AU - Zaccarini, Federica

AU - Bonazzi, Paola

AU - Grammatikopoulos, Tassos

AU - Tsikouras, Basilios

AU - Stanley, Chirs

AU - Garuti, Giorgio

N1 - Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2020/3/8

Y1 - 2020/3/8

N2 - The new mineral species, eliopoulosite, V 7 S 8, 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 6.55 Ni 0.19 Fe 0.12 Co 0.07 Mo 0.04) Σ = 6.97 S 8.03. The simplified formula is (V, Ni, Fe) 7 S 8 and the ideal formula is V 7 S 8, 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 P3 2 21, with a = 6.689(3) Å, c = 17.403(6) Å, V = 674.4(5) Å 3, 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).

AB - The new mineral species, eliopoulosite, V 7 S 8, 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 6.55 Ni 0.19 Fe 0.12 Co 0.07 Mo 0.04) Σ = 6.97 S 8.03. The simplified formula is (V, Ni, Fe) 7 S 8 and the ideal formula is V 7 S 8, 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 P3 2 21, with a = 6.689(3) Å, c = 17.403(6) Å, V = 674.4(5) Å 3, 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).

UR - http://www.scopus.com/inward/record.url?scp=85081239359&partnerID=8YFLogxK

U2 - https://doi.org/10.3390/min10030245

DO - https://doi.org/10.3390/min10030245

M3 - Article

VL - 10.2020

SP - 1

EP - 13

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 3

M1 - 245

ER -