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Crystal structure of barstowite (3PbCl2·PbCO3·H2O)

Published online by Cambridge University Press:  05 July 2018

I. M. Steele
Affiliation:
Department of Geophysical Sciences, The University of Chicago, Chicago IL 60637, USA
J. J. Pluth
Affiliation:
Department of Geophysical Sciences, The University of Chicago, Chicago IL 60637, USA Consortium for Advanced Radiation Sources, The University of Chicago, Chicago IL 60637, USA Materials Research Science and Engineering Center, The University of Chicago, Chicago IL 60637, USA
C. J. Stanley
Affiliation:
Department of Mineralogy, Natural History Museum, Cromwell Road, London SW7 5BD, UK

Abstract

The crystal structure of barstowite (3PbCl2·PbCO3·H2O, P21/m, a = 4.2023(5), b = 9.2020(7), c = 16.6608(6)(Å), β = 91.829(9)°) from Bounds Cliff, St Endellion, Cornwall, has been determined to an R = 0.036. The structure can be described in terms of three layers stacked along [001] in the sequence …CACBCACBC… to give a 16.7 Å repeat. Layer A consists of face-sharing PbCl8 distorted square antiprisms. Layer B is composed of Pb coordinated to 5 Cl and 2 O each with two H to form H2O groups. Layer C is formed by Pb coordinated to 5 Cl and 3 O which are from CO3 groups. The H positions are deduced and are H-bonded to O from carbonates. The structural details were in agreement with previous deductions based on infrared spectra.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1999

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