- © 2016 The Mineralogical Society
Berezanskite, ideally Ti2□2KLi3(Si12O30), is hexagonal, space group P6/mcc, a = 9.898(4), c = 14.276(6) Å, V = 1211.2(9) Å3, Z = 2. The crystal structure was refined to an R1 index of 2.08% based on 392 unique observed reflections. Berezanskite is isostructural with milarite, ideally ACa2BoCKT(2)(Be2Al)(T(1)Si12O30)(H2O)0–2. The structural unit is of the form [T(2)3T(1)12O30] with T(1) = Si and T(2) = Li, in which (LiO4) tetrahedra link [Si12O30] six-membered double-rings into a framework. The A, B and C sites occur in the interstices of the framework with the following site populations: A = Ti4+2, <A–O> = 1.938(2) Å; B = □2; C = K, <C–O> = 3.058(2) Å. In the T(2) = Li3 milarite-group minerals, the <C–O> distance is inversely related to the occupancy of the B site.