The crystal structure of hodgkinsonite Zn2Mn [(OH)2|SiO4]

Publisher Website
Google Scholar
Abstract
Hodgkinsonite, Zn 2 Mn[(OH) 2 |SiO 4 ], is a pneumatolytie mineral of Franklin, New Jersey, with lattice constants: a = 8.171, b = 5.316, c = 11.761 Å, β = 95° 15′; Z = 4, space group P 2 1 / a . Intensities hkl were collected with a single-crystal equi-inclination diffractometer. The structure was obtained from the three-dimensional Patterson synthesis by applying the minimum function. Atomic parameters and isotropic temperature factors were refined by least squares to R = 0.067. Correction for anomalous scattering of the Mn atoms was applied. The SiO 4 tetrahedron is almost regular with an average Si–O distance of 1.626 Å and average O–O distance of 2.655 Å. The two Zn atoms are surrounded by four O atoms forming a distorted tetrahedron. Average Zn–O distances are 1.969 Å and 1.974 Å and O–O distances 3.211 Å and 3.216 Å respectively. The Mn atom is octahedrally coordinated by five OH groups and one O atom. The average Mn–O distance is 2.222 Å and the corresponding O–O distance is 3.133 Å. The ZnO 4 tetrahedra share a corner with the SiO 4 tetrahedra and form two-dimensional networks Zn 2 SiO 4 , ( A ), parallel to (001). Similarly the MnO 6 octahedra form two-dimensional networks, ( B ), extending parallel to (001), and link two Zr 2 SiO 4 networks together. The structural principle is ‥ ABAABA ‥ in the direction of the c axis. Hodgkinsonite is not isotypic with norbergite, Mg 3 [(OH) 2 |SiO 4 ], and does not belong to the humite group.

This publication has 7 references indexed in Scilit: