Unit-cell intergrowth of pyrochlore and hexagonal tungsten bronze structures in secondary tungsten minerals
- CSIRO Minerals, Box 312, Clayton South, Vic. 3169 (Australia)
- Geosciences Department, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001 (Australia)
- Equipe CEA-CNRS NPSC SP2M/DRFMC/CEA, 17 rue des Martyrs, 38054 Grenoble (France)
Structural relations between secondary tungsten minerals with general composition A{sub x}[(W,Fe)(O,OH){sub 3}]{sub .y}H{sub 2}O are described. Phyllotungstite (A=predominantly Ca) is hexagonal, a=7.31(3)A, c=19.55(1)A, space group P6{sub 3}/mmc. Pittongite, a new secondary tungsten mineral from a wolframite deposit near Pittong in Victoria, southeastern Australia (A=predominantly Na) is hexagonal, a=7.286(1)A, c=50.49(1)A, space group P-6m2. The structures of both minerals can be described as unit-cell scale intergrowths of (111){sub py} pyrochlore slabs with pairs of hexagonal tungsten bronze (HTB) layers. In phyllotungstite, the (111){sub py} blocks have the same thickness, 6A, whereas pittongite contains pyrochlore blocks of two different thicknesses, 6 and 12A. The structures can alternatively be described in terms of chemical twinning of the pyrochlore structure on (111){sub py} oxygen planes. At the chemical twin planes, pairs of HTB layers are corner connected as in hexagonal WO{sub 3}.
- OSTI ID:
- 20902488
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 12; Other Information: DOI: 10.1016/j.jssc.2006.08.030; PII: S0022-4596(06)00470-1; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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