Crystal structure of magnesioneptunite

Crystal structure of magnesioneptunite

O. V. Karimova, O. V. Yakubovich, A. E. Zadov, A. G. Ivanova and V. S. Urusov
Crystallography Reports, 57 (4), 505-513 (2012),

Abstract:
The crystal structure of the new mineral magnesioneptunite (K_0.8Na_0.1−0.1)Na₂Li(Ti_0.39Mg_0.34Fe_0.27)₂(Ti_0.59Mg_0.22Fe_0.19)₂[Si4O₁₁]₂(O,OH) from the xenolith of Verkhnechegemskaya caldera (Lakarga Mountain, North Caucasus) has been investigated by X-ray diffraction (XCalibur-S diffractometer, R = 0.0244): a = 16.3271(7) Å, b = 12.4788(4) Å, c = 9.9666(4) Å, β = 115.651(5), V = 1830.5(1) ų, sp. gr. C2/c, Z = 4, and ρ_calcd = 3.152 g/cm³. The disordered distribution of Ti, Mg, and Fe atoms in the octahedra forming the basis of the cationic framework is established. It is shown that the isomorphic occupation of octahedral positions by cations of three types corresponds to the centrosymmetric crystal structure and is likely caused by the high-temperature crystallization of the mineral



Edited 1 time(s). Last edit at 07/18/2012 05:17PM by Jim Ferraiolo.