![]() ![]() 2009, 2010), the pegmatitic carbonatite of the Snowbird mine, Montana, (Metz et al. 2009), the alkaline granite-syenite pegmatites of the Mount Malosa pluton in Malawi (Guastoni et al. Parisite–(Ce), which is one of the most common fluorcarbonate species, is known from the carbonatite orebody of Mountain Pass, California (Castor 2008), the carbonatite complex Amba Dongar, India, (Doroshkevich et al. Only after 1890, further occurrences were discovered. ![]() “Parisite” has been named after the former mine owner and manager, Mr. The first description of “parisite” appeared in the middle of the nineteenth century: The Italian mineralogist Lavinio de Medici-Spada used this term in describing a specimen found in the Muzo emerald-mining area, Boyacá Department, Colombia (Bunsen 1854). This raises the question, whether or not a specific mineral name can be used for a “crystal” consisting of polysomatic layering sequences? The fluorine is commonly substituted by an OH − group and the extent of this substitution varies from negligible to predominance of OH − over F. The majority of REE fluorcarbonates are hence polycrystals. This consideration appeared practical as the above REE fluorcarbonates are characterised by complicated mixed-layer structures consisting of complex syntaxic intergrowths of virtually all members except of bastnäsite–synchysite intergrowths (Donnay and Donnay 1953). They have occasionally been considered to form one single “bastnäsite-synchisite series” (e.g. ![]() All of these minerals are characterised by a layered topology that is composed of bastnäsite ( B) and synchisite ( S) basic units (e.g. For instance, extensive research addressing the thermodynamic stability of fluorcarbonates has been conducted by Williams-Jones and Wood ( 1992) and Gysi and Williams-Jones ( 2015), in order to provide information on REE ore formation.īastnäsite, REECO 3F, and synchysite, CaREE(CO 3) 2F, represent end members of a polysomatic mineral series including parisite, CaREE 2(CO 3) 3F 2, and röntgenite, Ca 2REE 3(CO 3) 5F 3, as intermediate members. 1999 Castor 2008 Gysi and Williams-Jones 2015). The study of fluorcarbonate minerals has increased appreciably because the majority of REEs worldwide is contained in these minerals (Williams-Jones and Wood 1992 Smith et al. ![]() Parisite–(Ce), idealised formula CaCe 2(CO 3) 3F 2, belongs to the group of REE fluorcarbonate minerals. 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. 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. Parisite–(Ce), the B 3 S 4 phase and röntgenite–(Ce) show different BSE intensities from high to low. 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. 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. 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. 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. ![]()
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