ИСТИНА

A Na,Zr,Mn-lovozerite-like mineral with uncommon distribution of Na in structure was found in the Lovozero alkaline complex, Kola, Russia. Its crystal structure is studied using single-crystal X-ray analysis (Xcalibur S CCD diffractometer, MoKα-radiation). Unit-cell parameters are: a =10.1857(6) Å, c =13.139(1) Å, V = 1180.54 Å3, sp. gr. R3m. Crystal structure was solved by direct methods and refined up to R = 0.0730 (483 F > 4σF) in anisotropic approximation. The main structural features are reflected in its crystal chemical formula (Z=3): A(Na0.45K0.100.45)3B3 C(Na0.45Mn0.250.30)M(Zr0.95Nb0.05){Si6O12[(OH)0.78O0.22]3(OH)3}. In accordance with approved nomenclature of lovozerite group minerals1, the studied sample belongs to the zirsinalite-lovozerite subgroup being among cation-deficient (with vacant B sites) members.