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Kernowite, Cu2Fe(AsO4)(OH)4⋅4H2O, the Fe3+-analogue of liroconite from Cornwall, UK

Published online by Cambridge University Press:  12 May 2021

Michael S. Rumsey Open the ORCID record for Michael S. Rumsey [Opens in a new window] ,
Mark D. Welch ,
John Spratt ,
Annette K. Kleppe  and
Martin Števko
Michael S. Rumsey*
Affiliation:
Department of Earth Sciences, Natural History Museum, LondonSW7 5BD, UK
Mark D. Welch
Affiliation:
Department of Earth Sciences, Natural History Museum, LondonSW7 5BD, UK
John Spratt
Affiliation:
Core Research Laboratories, Natural History Museum, LondonSW7 5BD, UK
Annette K. Kleppe
Affiliation:
Diamond Lightsource UK, Harwell Science Park, Chilton, OxfordshireOX11 0DE, UK
Martin Števko
Affiliation:
Earth Science Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 840 05 Bratislava, Slovak Republic Department of Mineralogy and Petrology, National Museum, Cirkusová 1740, 193 00 Praha, Horní Počernice, Czech Republic
*
*Author for correspondence: Michael S. Rumsey, Email: m.rumsey@nhm.ac.uk
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Abstract

The occurrence, chemical composition and structural characterisation of the new mineral kernowite, ideally Cu2Fe(AsO4)(OH)4⋅4H2O, the Fe3+-analogue of liroconite, Cu2Al(AsO4)(OH)4⋅4H2O, are described. Kernowite (IMA2020-053) occurs on specimens probably sourced from the Wheal Gorland mine, St Day, Cornwall, UK, in the cavities of a quartz-gossan rich in undifferentiated micro-crystalline grey sulfides and poorly crystalline arsenic phases including both pharmacosiderite and olivenite-group minerals. The average composition of kernowite determined from several holotype fragments by electron microprobe analysis is Cu1.88(Fe0.79Al0.09)Σ0.88(As1.12O4)(OH)4⋅3.65H2O. The structure of kernowite has been determined in monoclinic space group I2/a (a non-standard setting of C2/c) by single-crystal X-ray diffraction (SCXRD) to R1 = 0.025, wR2 = 0.051 and Goodness-of-fit = 1.112. Unit-cell parameters from SCXRD are a = 12.9243(4) Å, b = 7.5401(3) Å, c = 10.0271(3) Å, β = 91.267(3)°, V = 976.91(6) Å3 and Z = 4. The chemical formula of this crystal indicated by SCXRD from refined site-scattering is Cu2(Fe3+0.84(1)Al0.16)AsO4(OH)4⋅4H2O. The network of hydrogen bonding has been determined and is similar to that reported for liroconite from Wheal Gorland by Plumhoff et al. (2020).

Keywords

kernowiteliroconiteCornwalliron aluminium arsenatemineral collectionsmineral museumUnited Kingdomnew mineral
Type
Article
Information
Mineralogical Magazine , Volume 85 , Issue 3 , June 2021 , pp. 283 - 290
Copyright
Copyright © The Author(s), 2021. Published by Cambridge University Press on behalf of The Mineralogical Society of Great Britain and Ireland

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Footnotes

Associate Editor: Juraj Majzlan

References

Anon. (1799) Report from the Committee appointed to enquire into the state of the copper mines and copper trade of this Kingdom. Ordered to be printed 7th May 1799. Parliamentary Papers printed by order of the House of Commons, 1731 to 1800, vol. 52.Google Scholar
Berry, L.G. (1938) Observations on conichalcite, cornwallite, euchroite, liroconite and olivenite. American Mineralogist, 36, 484–503.Google Scholar
Brown, I.D. and Altermatt, D. (1985) Bond-valence parameters obtained from a systematic analysis of the inorganic crystal structure database. Acta Crystallographica, B41, 244–247.CrossRefGoogle Scholar
Burns, P. C., Eby, R.K. and Hawthorne, F.C. (1991) Refinement of the structure of liroconite, a heteropolyhedral framework oxysalt mineral. Acta Crystallographica, C47, 916–919.Google Scholar
Count, de Bournon J-L. (1801) Description of the arseniates of copper and of iron from the County of Cornwall. Philosophical Transactions, 91, 169–192.Google Scholar
Degen, T., Sadki, M., Bron, E., König, U. and Néner, G. (2014) The HighScore suite. Powder Diffraction, 29 (Supplement 2), S13–S18. http://doi.org/10.1017/S0885715614000840CrossRefGoogle Scholar
Jameson, R. (1821) Manual of Mineralogy. A. Constable, Edinburgh pp.491.10.5962/bhl.title.49995CrossRefGoogle Scholar
Lafuente, B., Downs, R.T., Yang, H. and Stone, N. (2015) The power of databases: the RRUFF project. Pp 1–30 in: Highlights in Mineralogical Crystallography (Armbruster, T and Danisi, RM, editors). W. De Gruyter, Berlin, Germany.Google Scholar
Makreski, P., Jovanovski, S., Pejov, L., Petruševki, G., Ugarković, S. and Jovanovski, G. (2015) Theoretical and experimental study of the vibrational spectra of liroconite, Cu2Al(AsO4)(OH)4⋅4H2O and bayldonite, Cu3Pb[O(AsO3OH)2(OH)2]. Vibrational Spectroscopy, 79, 36–43.10.1016/j.vibspec.2015.04.006CrossRefGoogle Scholar
Momma, K. and Izumi, F. (2011) VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data. Journal of Applied Crystallography, 44, 1272–1276.10.1107/S0021889811038970CrossRefGoogle Scholar
Plumhoff, A.M., Dachs, E., Benisek, A., Plášil, J., Sejkora, J., Števko, M., Rumsey, M.S. and Majzlan, J. (2020) Thermodynamic properties, crystal structure and phase relations of pushcharovskite Cu(AsO3OH)(H2O)⋅0.5H2O, geminite Cu(AsO3OH)(H2O) and liroconite Cu2Al(AsO4)(OH)4⋅4H2O. European Journal of Mineralogy, 32, 285–304.10.5194/ejm-32-285-2020CrossRefGoogle Scholar
Robinson, K., Gibbs, G.V. and Ribbe, P.H. (1971) Quadratic elongation: a quantitative measure of distortion in coordination polyhedra. Science, 172, 567–570.10.1126/science.172.3983.567CrossRefGoogle ScholarPubMed
Rumsey, M.S., Welch, M.D., Spratt, J., Kleppe, A. and Števko, M. (2020) Kernowite, IMA 2020-053. CNMNC Newsletter No. 58; Mineralogical Magazine, 84, 971–975, https://doi.org/10.1180/mgm.2020.93Google Scholar
Sheldrick, G.M. (2015) Crystal structure refinement with SHELX. Acta Crystallographica, C71, 3–8.Google Scholar
Sowerby, J. (1804) British Mineralogy, Volume I. R.Taylor & Co, London, pp. 224.Google Scholar
Wilson, A.J.C. (editor) (1992) International Tables for Crystallography, Volume C: Mathematical, Physical and Chemical Tables. Kluwer Academic, Dordrecht, Netherlands.Google Scholar
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