A reinvestigation of gabrielsonite from the holotype specimen from Långban, central Sweden, using single-crystal synchrotron diffraction, electron-microprobe techniques and Fourier-transform infrared (FTIR) spectroscopy, Raman and Mo¨ssbauer spectroscopies show that the mineral is an anhydrous Fe3+-bearing arsenite and not a hydrous Fe2+-bearing arsenate, as originally proposed. The revised ideal chemical formula of gabrielsonite is PbFe3+(As3+O3)O. The mineral is related to the descloizite supergroup, but it differs through the valencies of the non-Pb cations Fe (M3+ vs. M2+) and As (3 + vs. 4 +) and through lower coordination of Pb (4 vs. 7–8) and As (3 vs. 4). The redefinition of gabrielsonite (proposal 17-G) has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association.
Autori interni: | PERCHIAZZI, NATALE (Primo) |
Autori: | Perchiazzi, Natale; Hålenius, Ulf; Vignola, Pietro; Demitri, Nicola |
Titolo: | Gabrielsonite revisited: crystal-structure determination and redefinition of chemical formula |
Anno del prodotto: | 2018 |
Abstract: | A reinvestigation of gabrielsonite from the holotype specimen from Långban, central Sweden, using single-crystal synchrotron diffraction, electron-microprobe techniques and Fourier-transform infrared (FTIR) spectroscopy, Raman and Mo¨ssbauer spectroscopies show that the mineral is an anhydrous Fe3+-bearing arsenite and not a hydrous Fe2+-bearing arsenate, as originally proposed. The revised ideal chemical formula of gabrielsonite is PbFe3+(As3+O3)O. The mineral is related to the descloizite supergroup, but it differs through the valencies of the non-Pb cations Fe (M3+ vs. M2+) and As (3 + vs. 4 +) and through lower coordination of Pb (4 vs. 7–8) and As (3 vs. 4). The redefinition of gabrielsonite (proposal 17-G) has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association. |
Digital Object Identifier (DOI): | 10.1127/ejm/2018/0030-2794 |
Appare nelle tipologie: | 1.1 Articolo in rivista |