gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1996.060.402.11 Mineralogy The Crystal Structure of Carminite: Refinement and Bond Valence Calculations Taylor Max R. Bevan D. J. M Department of Chemistry, The Flinders University of South Australia, GPO Box 2100 Adelaide, S. A. 5001, Australia Pring Allan Department of Mineralogy, South Australian Museum, North Terrace, S. A. 5000, Australia 10 1996 60 402 805 811 29 8 1995 15 11 1995 Copyright © 1996, The Mineralogical Society 1996 Abstract

The crystal structure of carminite, PbFe2(AsO4)2(OH)2 has been refined. The mineral is orthorhombic, Cccm with a = 16.591(2), b = 7.580(1), c = 12.285(1) Å, Z = 8; the structure has been refined to a conventional R = 3.3% using 913 observed reflections [I>2σ(I)]. The structure contains stepped chains of edge-sharing pairs of Fe(O,OH)6 octahedra; these chains are linked by AsO4 tetrahedra and Pb atoms in distorted square antiprismatic co-ordination. The hydrogen bonding network in the structure has been modelled using bond valence calculations.

 Keywords carminite crystal structure refinement hydrogen bonding network