Jasonsmithite, a new phosphate mineral with a complex microporous framework, from the Foote mine, North Carolina, USA

Jasonsmithite (IMA2019-121), Mn42+ZnAl(PO4)(4)(OH)(H2O)(7)center dot 3.5H(2)O, is a pegmatite-phosphate mineral from the Foote Lithium Company mine, Kings Mountain district, Cleveland County, North Carolina, U.S.A. It is interpreted as having formed by late-stage, low-temperature hydrothermal alteration. Crystals are colorless to light brown, slightly flattened prisms to about 1 mm in length with wedge-shaped terminations. The mineral is transparent with vitreous luster, white streak, Mohs hardness 2, brittle tenacity, irregular fracture, and perfect {001} cleavage. The density is 2.63(2) g/cm(3). Jasonsmithite is biaxial (-), with alpha = 1.561(2), p = 1.580(2), gamma = 1.581(2), measured in white light. The 2V is 25(5)degrees and dispersion is r < nu moderate. The optical orientation is Y = b, X boolean AND c = 18 degrees in obtuse R. The Raman spectrum is dominated by vibrational modes of PO4 and ZnO4 tetrahedra, AlO6 and MnO6 octahedra, and OH groups. Electron microprobe analyses gave the empirical formula (Mn3.09Fe0.87)(Sigma 3.96)Zn1.05Al0.98(PO4)(4)(OH)(H2O)(7)center dot 3.5H(2)O. The mineral is monoclinic, P2(1)/c, a= 8.5822(3), b = 13.1770(6), c = 20.3040(14) angstrom, beta = 98.485(7)degrees, V = 2271.0(2) angstrom(3), and Z = 4. The structure (R-1 = 0.0443 for 3685 />2 sigma/ reflections) contains zigzag chains of edge-sharing MnO6 octahedra that cornerlink to adjacent chains and to PO4 tetrahedra to form sheets, which are decorated by ZnO4 tetrahedra. The sheets are linked to one another via dimers of AlO6 octahedra, forming a framework with large channels containing H2O groups. With H2O groups removed, the framework has a void space of 70.2% per unit cell, and a framework density of 14.5 polyhedral atoms/1000 angstrom(3), which would place jasonsmithite among the most porous minerals.