The Crystal Structure of Kintoreite, PbFe3(PO4)2(OH,H2O)6

Kharisun*, M. R. Taylor, D. J. M. Bevan and A. Pring
Department of Chemistry, Flinders University, GPO Box 2100 Adelaide, South Australia 5000, Australia
Department of Mineralogy, South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
*Permanent address: Fakultas Pertanian, Universitas Djenderal Soedirman, P.O. Box 25, Purwokerto 53101, Jawa-Tengah, Indonesia

Abstract: The crystal structure of kintoreite, PbFe3(PO4)2(OH,H2O)6, has been refined. The mineral is rhombohedral, R3¯m with a = 7.3310(7), c = 16.885(2) Å, Z = 3; the structure has been refined to R = 3.0% and Rw = 3.0% using 183 observed reflections [I > 2σ(I)]. Kintoreite has the alunite-type structure which consists of sheets of corner-sharing Fe(O,OH)6 octahedra parallel to (001). The sheets are composed of clusters of three corner-linked octahedra which are tilted so that the three apical O atoms form the base of the XO4 tetrahedra. The clusters of octahedra are linked to similar groups by corner-sharing to form six membered rings. The Pb cations occupy the cavities between pairs of octahedral sheets and are surrounded by six oxygen atoms from the tetrahedra and six oxygen atoms from the octahedra to form a very distorted icosahedron. The mean bond lengths for the various coordination polyhedra are X-O 1.55 Å, (X= P, As, S); Fe-(O, OH) 2.01 Å; Pb-O 2.84 Å. The composition of the crystal used in the refinement was PbFe3(PO4)1.3(AsO4)0.4(SO4)0.3(OH,H2O)6. The XO4 anions are disordered, as in beudantite, rather than being ordered, as they are claimed to be in corkite.

Keywords: kintoreite • beudantite • corkite • crystal structure • Kintore opencut • New South Wales

Mineralogical Magazine; February 1997 v. 61; no. 404; p. 123-129; DOI: 10.1180/minmag.1997.061.404.12
© 1997, The Mineralogical Society
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