The parisite-(Ce) enigma: challenges in the identification of fluorcarbonate minerals.

Autor: Zeug M; Institut für Mineralogie und Kristallographie, Universität Wien, Althanstr. 14, 1090 Wien, Austria., Nasdala L; Institut für Mineralogie und Kristallographie, Universität Wien, Althanstr. 14, 1090 Wien, Austria., Ende M; Institut für Mineralogie und Kristallographie, Universität Wien, Althanstr. 14, 1090 Wien, Austria., Habler G; Department of Lithospheric Research, University of Vienna, Althanstr. 14, 1090 Wien, Austria., Hauzenberger C; NAWI Graz Geozentrum, Universitätsplatz 2, 8010, Graz, Austria., Chanmuang N C; Institut für Mineralogie und Kristallographie, Universität Wien, Althanstr. 14, 1090 Wien, Austria., Škoda R; Department of Geological Sciences, Masaryk University, Kotlářská 2, 61137 Brno, Czech Republic., Topa D; Natural History Museum Vienna, Burgring 7, 1010 Wien, Austria., Wildner M; Institut für Mineralogie und Kristallographie, Universität Wien, Althanstr. 14, 1090 Wien, Austria., Wirth R; Helmholtz-Zentrum Potsdam - GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany.
Jazyk: angličtina
Zdroj: Mineralogy and petrology [Mineral Petrol] 2021; Vol. 115 (1), pp. 1-19. Date of Electronic Publication: 2020 Oct 10.
DOI: 10.1007/s00710-020-00723-x
Abstrakt: A multi-methodological study was conducted in order to provide further insight into the structural and compositional complexity of rare earth element (REE) fluorcarbonates, with particular attention to their correct assignment to a mineral species. Polycrystals from La Pita Mine, Municipality de Maripí, Boyacá Department, Colombia, show syntaxic intergrowth of parisite-(Ce) with röntgenite-(Ce) and a phase which is assigned to B 3 S 4 (i.e., bastnäsite-3-synchisite-4; still unnamed) fluorcarbonate. Transmission electron microscope (TEM) images reveal well-ordered stacking patterns of two monoclinic polytypes of parisite-(Ce) as well as heavily disordered layer sequences with varying lattice fringe spacings. The crystal structure refinement from single crystal X-ray diffraction data - impeded by twinning, complex stacking patterns, sequential and compositional faults - indicates that the dominant parisite-(Ce) polytype M 1 has space group Cc . Parisite-(Ce), the B 3 S 4 phase and röntgenite-(Ce) show different BSE intensities from high to low. Raman spectroscopic analyses of parisite-(Ce), the B 3 S 4 phase and röntgenite-(Ce) reveal different intensity ratios of the three symmetric CO 3 stretching bands at around 1100 cm -1 . We propose to non-destructively differentiate parisite-(Ce) and röntgenite-(Ce) by their 1092 cm -1 / 1081 cm -1 ν 1 (CO 3 ) band height ratio.
(© The Author(s) 2020.)
Databáze: MEDLINE
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