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The crystal chemistry of elsmoreite from the Hemerdon (Drakelands) mine, UK: hydrokenoelsmoreite-3C and hydrokenoelsmoreite-6R

Published online by Cambridge University Press:  02 January 2018

Stuart J. Mills*
Geosciences, Museum Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia
Andrew G. Christy
Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601, Australia
Mike S. Rumsey
Earth and Planetary Mineralogy Division, Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
John Spratt
Core Research Laboratories, Facilities Department, Natural History Museum, Cromwell Road, London SW7 5BD, UK


A crystallographic and chemical study of two 'elsmoreite' samples (previously described as 'ferritungstite') from the Hemerdon mine (now known as the Drakelands mine), Devon, United Kingdom has shown them to be two different polytypes of hydrokenoelsmoreite. Hydrokenoelsmoreite-3C(HKE-3C) crystallizes in space group , with the unit-cell parameter a = 10.3065(3) Å. Hydrokenoelsmoreite-6R (HKE-6R) crystallizes in space group , with the unit-cell parameters a = 7.2882(2) Å and c = 35.7056(14)Å. Chemical analyses showed that both polytypes have Na and Fe/Al substitution giving the formulae: (Na0.28Ca0.04K0.02(H2O)0.201.46)∑2.00(W1.47Fe3+0.32Al0.21As5+0.01)∑2.00[O4.79(OH)1.21]∑6.00·(H2O)(3C) and (Na0.24Ca0.04K0.03(H2O)0.631.06)∑2.00(W1.42Fe3+0.49Al0.08As5+0.01)∑2.00[O4.65(OH)1.35]∑6.00·(H2O)(6R). The doubling of the unit cell in the 6R phase is due to ordering of Na and ( ,H2O) in the A site; no long-range ordering is observed between W and Fe/Al in the B site.

Research Article
Copyright © The Mineralogical Society of Great Britain and Ireland 2016

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Current address: Queensland Museum, 122 Gerler Road, Hendra, Queensland 4011, and School of Earth Sciences, University of Queensland, St Lucia, Queensland 4072, Australia


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