Regerite mineral

Regerite is a hydrated potassium ferric phosphate mineral with ideal formula KFe6(PO4)4(OH)7(H2O)6·4H2O, approved as IMA 2023-028 and retained in the September 2026 IMA list. Rewitzer et al. (2023) characterized crystals from a historical Kreuzberg pegmatite specimen from Pleystein, Germany. The natural material contains titanium; wavelength-dispersive analyses of 15 crystals are not independent occurrences or a synthesis experiment. Water was calculated from the structural model and an assumed charge-compensating substitution, rather than directly measured. Single-crystal synchrotron diffraction at 100 K supports monoclinic P21/c symmetry and a framework of iron-centred octahedra and phosphate tetrahedra with potassium and water in channels. Bond-valence sums support the ferric assignment, rather than a separate direct iron-valence assay. Twenty-five of the 27 ideal hydrogen positions were located and refined with restraints; H22 and H30b remained unresolved. The deposited all-Fe model and ideal formula do not represent the full measured titanium-bearing composition. The proposed titanium distribution, displacement and charge-compensation scheme remain interpretations, with displaced Ti not unambiguously confirmed. The text's O18-to-O33 water-site range overlaps its hydroxyl assignment; Table 4 and the deposited hydrogen model instead distinguish O17-to-O23 hydroxyl sites from O24-to-O33 water sites. Natural occurrence and crystal structure do not establish a formation, microbial extraction or recovery mechanism. No criticality designation is inherited from constituent elements.

Record source: data/records/regerite.yaml