Synchysite-(Ce) mineral

A calcium-cerium fluorcarbonate mineral with the ideal IMA-CNMNC September 2026 formula CaCe(CO3)2F. The authority lists renamed status and identifier 1982-030; these identify this species, not the Nd- or Y-dominant synchysite species, bastnäsite, a rare-earth element or a mixed ore concentrate. Conconi et al. (2025) examined five natural crystals from miarolitic cavities in the Cuasso al Monte granophyre, Italy. Four crystals (FCBN1–FCBN4) supplied monoclinic C2/c average-structure refinements; Raman and SEM–EDS characterization used a subset, and TEM–EDS/electron diffraction used two lamellae from the separate FCBN5 crystal, as specified in Table A1. The crystals show chemical zoning, stacking disorder and inclusions. For FCBN3, Table 3 reports mean Ce contents of 0.44 atoms per formula unit in the core (13 spots) and 0.30 in the outer rim (11 spots), normalized to two cations; these are local composition averages, not recovery measurements or a uniform species formula. Low measured fluorine may reflect beam-induced loss. Fictitious scattering-site occupancies and calculated densities from the diffraction refinements do not directly represent measured chemistry. The proposed screw-dislocation growth sequence and Th-related loss of crystallinity are interpretations of natural microstructure; beam damage and other defects limit causal attribution. No controlled microbial, extraction, or recovery experiment is curated here. Underlying FCF diffraction files were available only upon request and were not acquired; published tables and Appendix A were inspected. No criticality designation is transferred from contained rare-earth elements.

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