Ancylite-(Ce) mineral

A natural cerium-strontium carbonate mineral with the ideal IMA-CNMNC September 2026 formula CeSr(CO3)2(OH)(H2O). The authority lists renamed status and 1987 special procedure, not a numbered approval accession. The 2024 approved ancylite-supergroup nomenclature distinguishes this Sr-dominant, Ce-dominant species from Ca-dominant calcioancylites and from kozoites. In its general formula, x is the trivalent-cation content per two cations; the ancylite group spans 1 <= x <= 1.5, whereas the kozoite group spans 1.5 < x <= 2. Dal Negro et al. (1975) studied a natural crystal from a nepheline-syenite pegmatite at Mont Saint-Hilaire, Quebec. Their Table 2 composition, La0.56Ce0.82Sr0.40Ca0.22(CO3)2(OH)1.38 ·0.62H2O, is a mixed-REE specimen formula, distinct from the ideal endmember. Five-grain microprobe averages were normalized using a separate thermogravimetric loss; water and carbon dioxide could not be individually determined from that curve. The text's assumed 20:80 water-to-carbon-dioxide loss partition does not match the individual volatile values in Table 1. Those values are not independent measured water and carbon dioxide contents. A crystal fragment was refined in orthorhombic Pmcn, a nonstandard setting of Pnma, to R = 0.059 using 498 observed reflections. The model places mixed heavy cations on a shared site, with eight carbonate oxygen neighbours and two hydroxyl or water oxygen neighbours; it does not locate hydrogen atoms or independently resolve the separate cation occupancies. Tables 3–6 include coordinates, displacement parameters, distances and structure factors. Structural comparisons with aragonite and bastnaesite are interpretations, not observed mineral conversions. No mineral-specific extraction experiment, microbial mechanism, recovery yield, industrial deployment or inherited criticality designation is asserted.

Record source: data/records/ancylite-ce.yaml