Structure and Twinning in Spencerite

L. Fanfani, A. Nunzi and P. F. Zanazzi
Istituto di Mineralogia, Università di Perugia, Italy

Summary: A refinement of the crystal structure of spencerite, Zn4(PO4)2(OH)2·3H2O, was performed on a twin crystal from Salmo, British Columbia. Three-dimensional intensity data were collected by a Weissenberg apparatus. The R index was 0·098 for 335 independent observed reflections. The crystal structure previously determined is essentially confirmed. Co-ordination around Zn is both octahedral and tetrahedral. The atomic arrangement consists of complex sheets of co-ordination octahedra and tetrahedra around Zn and P atoms connected by layers of water molecules. The frequent occurrence of twinning in spencerite is explained from structural considerations.

Mineralogical Magazine; June 1972 v. 38; no. 298; p. 687-692; DOI: 10.1180/minmag.1972.038.298.05
© 1972, The Mineralogical Society
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