gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1997.061.408.07 The Crystal Structure of Mawbyite, PbFe2(AsO4)2(OH)2 Kharisun * Taylor M. R. Bevan D. J. M. Department of Chemistry, Flinders University, GPO Box 2100 Adelaide, South Australia 5000, Australia Rae A. D. Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia Pring A. Department of Mineralogy, South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia

Permanent address: Fakultas Pertanian, Universitas Djenderal Soedirman, P.O. Box 125, Purwokerto 53123, Jawa-Tengah, Indonesia.

 10 1997 61 408 685 691 14 11 1996 11 2 1997 Copyright © 1997, The Mineralogical Society 1997 Abstract

The crystal structure of mawbyite, PbFe2(AsO4)2(OH)2 has been refined. The mineral is monoclinic, C2/m with a = 9.066(4), b = 6.286(3) c = 7.564(3) Å, β = 114.857(5)°, Z = 2; the structure has been refined to a conventional R = 4.3% using 361 observed reflections [I> 3σ(I)]. The structure contains chains of edgesharing Fe(O,OH)6 octahedra which 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. Mawbyite is confirmed to be isostructural with tsumcorite and dimorphous with carminite and the relationship between these two structures is discussed.

 Keywords mawbyite crystal structure Broken Hill New South Wales arsenate