Calcioveatchite mineral

Calcioveatchite is the approved calcium-strontium borate species with ideal formula SrCaB11O16(OH)5·H2O and IMA identifier 2020-011 in the September 2026 IMA-CNMNC list. It is distinct from the Sr-dominant species veatchite, elemental boron or strontium, and the broad borates commodity. Pekov et al. (2024) characterized natural type material from borehole 130 at 911 m depth in the Nepskoe potassium salt deposit, Siberia, Russia; the Fersman Mineralogical Museum holotype is 97013. The crystals were separated from a water-insoluble residue of the host salt rock. This sample preparation is not a quantified boron extraction or recovery experiment. Electron microprobe analysis of the holotype, averaged over four spots, gave 7.05 wt% CaO, 20.70 wt% SrO and 61.96 wt% B2O3 (Table 1, column 1). Its 10.22 wt% H2O was calculated from the structure because the small crystal could not be analyzed directly for water. A separate gross multi-crystal sample gave 10.07 wt% H2O by the Penfield method, averaging three analyses; these are not two measurements of the same preparation. The holotype empirical formula based on the calculated water is Sr1.23Ca0.78B10.99O16(OH)5·H2O, rather than an experimentally pure ideal end member. Single-crystal X-ray diffraction at 293(2) K supports monoclinic P21, Z = 2, with the eleven-coordinate cation site Sr dominant [Sr0.902(8)Ca0.098] and the ten-coordinate site Ca dominant [Ca0.686(7)Sr0.314]. Hydrogen positions were located in difference Fourier maps and refined with distance restraints. The site ordering distinguishes this species from veatchite; the paper's formal compositional boundary is Sr1.5Ca0.5B11O16(OH)5·H2O. Its new calcioveatchite observations are from Nepskoe. The inferred possibility of calcioveatchite zones in older Canadian material does not establish the modern identity of every previously studied veatchite specimen. The prose SrO range down to 17.1 wt% appears to include the ideal calculated Table 1 column 2 value of 17.11 wt%; that number is not adopted here as a measured endpoint. Tables 3-7 and Figures 7-8 support the reported structure, but an original CIF/reflection dataset was not acquired and the refinement was not independently repeated. Natural characterization and occurrence do not establish microbial activity, industrial boron recovery or a jurisdiction-specific criticality designation.

Record source: data/records/calcioveatchite.yaml