TY - JOUR

T1 - Stibioústalečite, Cu6 Cu6 (Sb2 Te2)Se13, the first Te–Se member of tetrahedrite group, from the Ústaleč, Czech Republic

AU - Sejkora, Jiří

AU - Plášil, Jakub

AU - Makovicky, Emil

N1 - Publisher Copyright: © 2022, Czech Geological Survey. All rights reserved.

PY - 2022

Y1 - 2022

N2 - Stibioústalečite, Cu12 (Sb2 Te2)Se13, was approved as a new mineral species from the Ústaleč mine, 15 km west of Horažďovice, SW Bohemia, Czech Republic. It occurs as metallic anhedral grains up to 0.1–0.3 mm in size, dark grey in color, in a calcite gangue. It is directly associated with hakite-(Hg), berzelianite, the not-yet approved phase Cu12 (As2 Te2) Se13 and uraninite. Stibioústalečite is brittle, with an indistinct cleavage and a conchoidal fracture; the calculated density is 5.676 g/cm3. In reflected light, stibioústalečite is isotropic, and grey in color; internal reflections were not observed. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 33.3; 546: 33.2; 589: 33.1; 650: 33.0. Electron microprobe analysis for holotype material (grain used for single-crystal X-ray study) gave (in wt. % – average of 7 spot analyses): Cu 34.10, Ag 1.22, Fe 0.04, Zn 0.09, Hg 0.33, Sb 9.39, As 0.70, Te 12.41, S 3.76, Se 37.59, total 99.63. On the basis of (As + Sb + Te) = 4 atoms per formula unit (apfu), the empirical formula of stibioústalečite is M(2) (Cu5.75 Ag0.25)Σ6 M(1) (Cu5.93 Hg0.04 Zn0.03 Fe0.02)Σ6.02 X(3) (Te2.12 Sb1.68 As0.20)Σ4 (Se10.36 S2.55)Σ12.91. The ideal formula is Cu6 Cu6 (Sb2 Te2) Se13, which requires Cu 33.33, Sb 10.64 Te 11.16 Se 44.87, total 100 wt. %. Stibioústalečite is cubic, I4̄ 3m, with unit-cell parameters a = 10.828(4) Å, V = 1269.6(9) Å3, Z = 2. The crystal structure of stibioústalečite was studied by single--crystal X-ray diffraction data and it is isotypic with other members of the tetrahedrite group. The mineral is named after its type locality Ústaleč and its chemical composition, being the (Sb/Te) end-member in the possible ústalečite series.

AB - Stibioústalečite, Cu12 (Sb2 Te2)Se13, was approved as a new mineral species from the Ústaleč mine, 15 km west of Horažďovice, SW Bohemia, Czech Republic. It occurs as metallic anhedral grains up to 0.1–0.3 mm in size, dark grey in color, in a calcite gangue. It is directly associated with hakite-(Hg), berzelianite, the not-yet approved phase Cu12 (As2 Te2) Se13 and uraninite. Stibioústalečite is brittle, with an indistinct cleavage and a conchoidal fracture; the calculated density is 5.676 g/cm3. In reflected light, stibioústalečite is isotropic, and grey in color; internal reflections were not observed. Reflectance data for the four COM wavelengths in air are [λ (nm): R (%)]: 470: 33.3; 546: 33.2; 589: 33.1; 650: 33.0. Electron microprobe analysis for holotype material (grain used for single-crystal X-ray study) gave (in wt. % – average of 7 spot analyses): Cu 34.10, Ag 1.22, Fe 0.04, Zn 0.09, Hg 0.33, Sb 9.39, As 0.70, Te 12.41, S 3.76, Se 37.59, total 99.63. On the basis of (As + Sb + Te) = 4 atoms per formula unit (apfu), the empirical formula of stibioústalečite is M(2) (Cu5.75 Ag0.25)Σ6 M(1) (Cu5.93 Hg0.04 Zn0.03 Fe0.02)Σ6.02 X(3) (Te2.12 Sb1.68 As0.20)Σ4 (Se10.36 S2.55)Σ12.91. The ideal formula is Cu6 Cu6 (Sb2 Te2) Se13, which requires Cu 33.33, Sb 10.64 Te 11.16 Se 44.87, total 100 wt. %. Stibioústalečite is cubic, I4̄ 3m, with unit-cell parameters a = 10.828(4) Å, V = 1269.6(9) Å3, Z = 2. The crystal structure of stibioústalečite was studied by single--crystal X-ray diffraction data and it is isotypic with other members of the tetrahedrite group. The mineral is named after its type locality Ústaleč and its chemical composition, being the (Sb/Te) end-member in the possible ústalečite series.

KW - chemical composition

KW - Czech Republic

KW - new mineral

KW - stibioústalečite

KW - tetrahedrite group

KW - Ústaleč

U2 - 10.3190/jgeosci.359

DO - 10.3190/jgeosci.359

M3 - Journal article

AN - SCOPUS:85143975145

VL - 67

SP - 275

EP - 283

JO - Journal of Geosciences (Czech Republic)

JF - Journal of Geosciences (Czech Republic)

SN - 1802-6222

IS - 4

ER -