The Crystal Structure of Carminite: Refinement and Bond Valence Calculations

Max R. Taylor, D. J. M Bevan and Allan Pring
Department of Chemistry, The Flinders University of South Australia, GPO Box 2100 Adelaide, S. A. 5001, Australia
Department of Mineralogy, South Australian Museum, North Terrace, S. A. 5000, Australia

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

Mineralogical Magazine; October 1996 v. 60; no. 402; p. 805-811; DOI: 10.1180/minmag.1996.060.402.11
© 1996, The Mineralogical Society
Mineralogical Society (www.minersoc.org)