Ecdemite from Harstigen, Värmland, Central Sweden was studied through Raman and FTIR spectroscopy, electron microprobe techniques, synchrotron powder and single crystal diffraction. The ideal mineral formula proposed by Palache et al. (1951), Pb6Cl4As2O7, is confirmed. In contrast to previous suggestions, the present study demonstrates that the mineral is monoclinic, with space group P21 and unit-cell parameters a = 10.8276 (38) Å, b = 10.8265 (21) Å, c = 6.9705 (14) Å, Β = 113.261° (24). The crystal structural study of ecdemite shows that the mineral can be considered as made up by regularly alternating, with 1:1 ratio, Cl layers and litharge-like defective layers, also hosting As cations. These features indicate that ecdemite can be considered as a new member of the of layered lead oxyhalides group.
Crystal chemical study of ecdemite from Harstigen, a new natural member of the layered lead oxyhalides structural group
Perchiazzi N.
Primo
Writing – Original Draft Preparation
;
2019-01-01
Abstract
Ecdemite from Harstigen, Värmland, Central Sweden was studied through Raman and FTIR spectroscopy, electron microprobe techniques, synchrotron powder and single crystal diffraction. The ideal mineral formula proposed by Palache et al. (1951), Pb6Cl4As2O7, is confirmed. In contrast to previous suggestions, the present study demonstrates that the mineral is monoclinic, with space group P21 and unit-cell parameters a = 10.8276 (38) Å, b = 10.8265 (21) Å, c = 6.9705 (14) Å, Β = 113.261° (24). The crystal structural study of ecdemite shows that the mineral can be considered as made up by regularly alternating, with 1:1 ratio, Cl layers and litharge-like defective layers, also hosting As cations. These features indicate that ecdemite can be considered as a new member of the of layered lead oxyhalides group.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
