title: Redetermination of katayamalite, KLi3Ca7Ti2(SiO3)12(OH)2.
abstract: The crystal structure of katayamalite, ideally KLi3Ca7Ti2(SiO3)12(OH)2 (potassium trilithium hepta-calcium dititanium dodeca-silicate di-hydroxide), 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 inter-connected 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.
authors.affiliation: Department of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721-0077, USA.
authors.forename: Marcelo B
authors.initials: MB
authors.lastname: Andrade
authors.forename: Donald
authors.initials: D
authors.lastname: Doell
authors.forename: Robert T
authors.initials: RT
authors.lastname: Downs
authors.forename: Hexiong
authors.initials: H
authors.lastname: Yang
references.citation: Phys Rev B Condens Matter. 1993 Apr 1;47(13):7869-7877
references.pmid: 10004792
references.citation: Acta Crystallogr A. 2008 Jan;64(Pt 1):112-22
references.pmid: 18156677