Referenza:
▪ Sejkora, J., Mauro, D., Biagioni, C. (2023): Single-crystal structure refinement of bukovite, (Cu3Fe)Σ4Tl2Se4. Journal of Geosciences, 68, 179-184.
Abstract:
Single-crystal X-ray diffraction study of bukovite, ideally (Cu3Fe)Σ4Tl2Se4, was performed using a specimen from the Ústaleč uranium deposit, 15 km west of Horažďovice, SW Bohemia, Czech Republic. In the studied specimens, bukovite occurs in calcite gangue with uraninite associated with bytízite, chaméanite, clausthalite, hakite-(Hg) and umangite. Electron microprobe analysis gave (in wt. % – average of 20 spot analyses): Cu 19.90, Tl 41.21, Fe 5.55, S 0.31, Se 31.60, total 98.57. On the basis of 10 atoms per formula unit, the empirical formula of bukovite is (Cu3.06Fe0.97)Σ4.03Tl1.97(Se3.91S0.09)Σ4.00 (Z = 1). Unit-cell parameters are a = 3.9694(8), c = 13.694(3) Å, V = 215.77(10) Å3, space group I4/mmm. The crystal structure was refined by single-crystal X-ray diffraction data to R1 = 0.0264 for 92 unique reflections with Fo > 4σ(Fo) mackinawite-like {001} layers of edge-sharing (Cu,Fe)-centered tetrahedra, with Tl atoms hosted in eight-fold cubic coordinated sites intercalated between these tetrahedral layers. The role of Fe is discussed and the chemical formula (Cu3Fe)Σ4Tl2Se4 is proposed.
▪ Sejkora, J., Mauro, D., Biagioni, C. (2023): Single-crystal structure refinement of bukovite, (Cu3Fe)Σ4Tl2Se4. Journal of Geosciences, 68, 179-184.
Abstract:
Single-crystal X-ray diffraction study of bukovite, ideally (Cu3Fe)Σ4Tl2Se4, was performed using a specimen from the Ústaleč uranium deposit, 15 km west of Horažďovice, SW Bohemia, Czech Republic. In the studied specimens, bukovite occurs in calcite gangue with uraninite associated with bytízite, chaméanite, clausthalite, hakite-(Hg) and umangite. Electron microprobe analysis gave (in wt. % – average of 20 spot analyses): Cu 19.90, Tl 41.21, Fe 5.55, S 0.31, Se 31.60, total 98.57. On the basis of 10 atoms per formula unit, the empirical formula of bukovite is (Cu3.06Fe0.97)Σ4.03Tl1.97(Se3.91S0.09)Σ4.00 (Z = 1). Unit-cell parameters are a = 3.9694(8), c = 13.694(3) Å, V = 215.77(10) Å3, space group I4/mmm. The crystal structure was refined by single-crystal X-ray diffraction data to R1 = 0.0264 for 92 unique reflections with Fo > 4σ(Fo) mackinawite-like {001} layers of edge-sharing (Cu,Fe)-centered tetrahedra, with Tl atoms hosted in eight-fold cubic coordinated sites intercalated between these tetrahedral layers. The role of Fe is discussed and the chemical formula (Cu3Fe)Σ4Tl2Se4 is proposed.
Statistiche: Inviato da Marco E. Ciriotti — gio 14 dic, 2023 9:23 — Risposte 1 — Visite 33