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Ashoverite, a New Mineral, and Other Polymorphs of Zn(OH)2 from Milltown, Ashover, Derbyshire

Published online by Cambridge University Press:  05 July 2018

A. M. Clark
Affiliation:
Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD
E. E. Fejer
Affiliation:
Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD
G. Cressey
Affiliation:
Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD
P. C. Tandy
Affiliation:
Department of Mineralogy, British Museum (Natural History), Cromwell Road, London SW7 5BD

Abstract

Four polymorphs of Zn(OH)2 have now been recorded from an oxidised vein exposure near Milltown, Ashover, Derbyshire; sweetite, wülfingite, γ-Zn(OH)2, and ashoverite. The last is a new mineral, a tetragonal modification of Zn(OH)2 containing minor quantities of Pb, Cd and Ca. Its unit cell dimensions are a 6.825(2) and c 33.36(4) Å, giving V = 1554 Å3; Z = 32; space group I41/amd, I41md, or I4¯2d; Dmeas. 3.3, Dcalc 3.44 g cm−3. Ashoverite occurs as colourless platy crystals associated with fluorite; it is uniaxial positive with ω 1.629(2), ε 1.639(2). The chemical composition of sweetite is compared with that of ashoverite.

Type
New Minerals
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1988

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