Description and crystal structure of liversidgeite, Zn6(PO4)4•7H2O, a new mineral from Broken Hill, New South Wales, Australia

Liversidgeite, ideally Zn-6(PO4)(4)center dot 7H(2)O, is a new mineral from Block 14 Opencut, Broken Hill, New South N ales, Australia. The mineral Occurs as white, thin, bladed crystals and as hemispherical aggregates of radiating crystals in cavities in sphalerite-galena ore. Associated minerals are anglesite, pyromorphite, greenockite, sulfur, and all unknown Zn phosphate sulfate. Individual crystals are Up to 0.1 min in length and 0.05 mm across. Liversidgene is transparent to translucent, with a vitreous luster and a white streak. It is brittle with ail irregular fracture, the Mohs hardness is similar to 3-3.5. and the observed and calculated densities are 3.21(2) and 3.28 g/cm(3) In alysis by electron respectively. Chemical antron microprobe gave ZnO 54.62 MnO 0.49, PbO 0.18, PO, 32.62, As2O5 0.65, SO3, 0.35 H2O 14.04, total 102.95 wt%, with H2O content derived from the refined crystal structure. The empirical formula calculated oil the basis of 23 O atoms is Pb-0.01(Zn5.86Mn0.00)(Sigma 5.92)(P4.01As0.05S0.04)(Sigma 4.10)O-16.20 center dot 6.8H(2)O. Liver is triclinic, space group P (1) over bar with a = 8.299(1) b = 9.6 16(1), c = 12.175(1) (A) over cap. alpha= 7 1.68(1) 82.02(1), gamma= 80.18(1)degrees, V= 905.1(2)angstrom(3) (single-crystal data), and Z = 2. The six strongest lines in the X-ray powder diffraction pattern are [(d(angstrom), (I) (hkl)]: 8.438 (80) (011), 3.206 (60) (01 (3) over bar), 2.967 (75) (2 (1) over bar2, 114), 2.956 (75) (21 (2) over bar), 2.550 (85) (233, 2 (1) over bar3) 2.537 (100) (22 (1) over bar. 0 14, 31 (1) over bar). Thle crystal Structure of liversidgeite was refined to,in R I index of 5.95% based on 3054 observed F-o > 4(sigma 7(o)) reflections measured with MoK alpha X-radiation. The structure is based oil two distinct, infinite zigzag chains of edge-sharing Zn, ( = unspecified anion) octahedra that extend in the a direction. The chains link to each Other via common corners and also via corner-sharing PO, tetrahedra, forming sheets parallel to the (011) plane. The sheets link via [Zn-2 phi(8)] dirneric building units, comprising edge-sharing Zr phi(5) trigonal bipyrainids and Zn tetrahedra, results in an open framework. Large ellipsoidal channels extend along the a direction and are occupied by interstitial H2O groups and the H atoms or the H2O groups that coordinate to the Zn cations. Ail extensive network of hydrogen bonds provides additional linkage between the sheets in the structure, via the interstitial H2O group. The topology of the liversidgeite Structure is identical to that of'synthetic, monoclinic Zn2Co4(PO4)(4)(H2O)(4)center dot 2H(2)O.