Celleriite, ▭(Mn22+ Al)Al6(Si6O18)(BO3)3(OH)3(OH), a new mineral species of the tourmaline supergroup

Celleriite, rectangle(Mn-2(2+) Al)Al-6(Si6O18)(BO3)(3)(OH)(3)(OH), is a new mineral of the tourmaline supergroup. It was discovered in the Rosina pegmatite, San Piero in Campo, Elba Island, Italy (holotype specimen), and in the Pikarec pegmatite, western Moravia, Czech Republic (co-type specimen). Celleriite in hand specimen is violet to gray-blue (holotype) and dark brownish-green (co-type) with a vitreous luster, conchoidal fracture, and white streak. Celleriite has a Mohs hardness of similar to 7 and a calculated density of 3.13 and 3.14 g/cm(3) for holotype and its co-type, respectively. In plane-polarized light in thin section, celleriite is pleochroic (O = pale violet and E = light gray-blue in holotype; O = pale green and E = colorless in co-type) and uniaxial negative. Celleriite has trigonal symmetry: space group R3m, Z = 3, a = 15.9518(4) and 15.9332(3) angstrom, c = 7.1579(2) and 7.13086(15) angstrom, V = 1577.38(9) and 1567.76(6) angstrom(3) for holotype and co-type, respectively (data from single-crystal X-ray diffraction). The crystal structure of the holotype specimen was refined to R1 = 2.89% using 1696 unique reflections collected with MoKa X-ray intensity data. Structural, chemical, and spectroscopic analyses resulted in the formulas: (X)(rectangle Na-0.58(0.42))(Sigma 1.00)(Y)(Mn1.392+Fe0.162+Mg0.01Al1.14Fe0.013+Li0.28Ti0.01)(Sigma 3.00)Al-Z(6)[T(Si5.99Al0.01)(Sigma 6.00)O-18](BO3)(3)(OH)(3) (W)[(OH)(0.65)F0.03O0.32](Sigma 1.00) (for holotype) and (X)(rectangle Na-0.51(0.49))(Sigma 1.00)(Y)( (Mn0.902+Fe0.502+AlFe0.043+Li0.17Zn0.04)-Fe-1.36)(Sigma 3.00)Al-Z(6)[T(Si5.75B0.25)(Sigma 6.00)O-18](BO3)(3)(OH)(3) W[(OH)(0.35)F0.17O0.48](Sigma 1.00) (for co-type) Celleriite is a hydroxy species belonging to the X-site vacant group of the tourmaline supergroup. The new mineral was approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association, proposal no. 2019-089. In the Rosina pegmatite, celleriite formed an overgrowth at the analogous pole of elbaite-fluor-elbaite-rossmanite crystals during the latest stage of evolution of pegmatite cavities after an event of a pocket rupture. In the Pikarec pegmatite, celleriite occurs as an intermediate growth sector of elbaite, princivalleite, and fluor-elbaite.

Automated summary

Celleriite is a new mineral of the tourmaline supergroup, found in Italy and the Czech Republic, with violet to gray-blue or dark brownish-green color. It has high Mohs hardness and density, with a trigonal crystal structure.