Probertite mineral

Probertite is the NaCaB5O7(OH)4(H2O)3 mineral species in the September 2026 IMA-CNMNC list, with grandfathered status G and original-description year 1929, not a sequential approval identifier. It is distinct from ulexite, elemental boron, the borates commodity and mixed ores containing probertite. Gatta et al. studied natural Kramer Deposit material from collection specimen 11717, using separate crystals for X-ray diffraction at 293 K and neutron diffraction at 20 K. Both refinements used monoclinic P21/c; the model contains pentaborate chains with three tetrahedral and two triangular boron sites, four hydroxyl groups and three water molecules per formula unit. Ten hydrogen sites were first located using neutron data and then incorporated into the X-ray refinement. Chemical analyses are specimen-specific: electron-probe results give CaO 15.8(2) and Na2O 8.6(3) wt%, while the separate trace-element table reports a mean lithium concentration of 0.392 wt ppm from ten analyses. Near-ideal major-cation composition does not mean zero trace elements or establish purity for every deposit. The paper reports limitations of its neutron extinction correction; the deposited CIFs and final publisher version were not acquired. This identity and characterization record makes no criticality, microbial extraction, isolated-product recovery or demonstrated radiation-shielding deployment claim.

Record source: data/records/probertite.yaml