Redetermination of katayamalite, KLi(3)Ca(7)Ti(2)(SiO(3))(12)(OH)(2)

The crystal structure of katayamalite, ideally KLi(3)Ca(7)Ti(2)(SiO(3))(12)(OH)(2) (potassium trilithium hepta­calcium dititanium dodeca­silicate di­hydroxide), was previously reported in triclinic symmetry (C-1), with isotropic displacement parameters for all atoms and without the H-atom position [Kato & Murakami (1985 ▶). Mineral. J. 12, 206–217]. The present study redetermines the katayamalite structure with monoclinic symmetry (space group C2/c) based on single-crystal X-ray diffraction data from a sample from the type locality, Iwagi Island, Ehime Prefecture, Japan, with anisotropic displacement parameters for all non-H atoms, and with the H atoms located by difference Fourier analysis. The structure of katayamalite contains a set of six-membered silicate rings inter­connected by sheets of Ca atoms on one side and by an ordered mixture of Li, Ti and K atoms on the other side, forming layers which are stacked normal to (001). From the eight different metal sites, three are located on special positions, viz. one K and one Li atom on twofold rotation axes and one Ca atom on an inversion center. The Raman spectrum of kataymalite shows a band at 3678 cm(−1), similar to that observed for hydroxyl-amphiboles, indicating no or very weak hydrogen bonding.