Hostname: page-component-8448b6f56d-wq2xx Total loading time: 0 Render date: 2024-04-23T07:54:36.869Z Has data issue: false hasContentIssue false
  • English
  • Français

Bulachite, [Al6(AsO4)3(OH)9(H2O)4]⋅2H2O from Cap Garonne, France: Crystal structure and formation from a higher hydrate

Published online by Cambridge University Press:  30 June 2020

Ian E. Grey Open the ORCID record for Ian E. Grey [Opens in a new window] ,
Emre Yoruk ,
Stéphanie Kodjikian ,
Holger Klein ,
Catherine Bougerol ,
Helen E.A. Brand ,
Pierre Bordet ,
William G. Mumme ,
Georges Favreau  and
Stuart J. Mills
Ian E. Grey*
Affiliation:
CSIRO Mineral Resources, Private Bag 10, Clayton South, Victoria3169, Australia
Emre Yoruk
Affiliation:
Université Grenoble Alpes and CNRS, Institut Néel, 38000, Grenoble, France
Stéphanie Kodjikian
Affiliation:
Université Grenoble Alpes and CNRS, Institut Néel, 38000, Grenoble, France
Holger Klein
Affiliation:
Université Grenoble Alpes and CNRS, Institut Néel, 38000, Grenoble, France
Catherine Bougerol
Affiliation:
Université Grenoble Alpes and CNRS, Institut Néel, 38000, Grenoble, France
Helen E.A. Brand
Affiliation:
Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria3168, Australia
Pierre Bordet
Affiliation:
Université Grenoble Alpes and CNRS, Institut Néel, 38000, Grenoble, France
William G. Mumme
Affiliation:
CSIRO Mineral Resources, Private Bag 10, Clayton South, Victoria3169, Australia
Georges Favreau
Affiliation:
421 avenue Jean Monnet, 13090 Aix-en-Provence, France
Stuart J. Mills
Affiliation:
Geosciences, Museums Victoria, GPO Box 666, Melbourne, Victoria3001, Australia
*
*Author for correspondence: Ian E. Grey, Email: ian.grey@csiro.au
Get access Rights & Permissions [Opens in a new window]

Abstract

Bulachite specimens from Cap Garonne, France, comprise two intimately mixed hydrated aluminium arsenate minerals with the same Al:As ratio of 2:1 and with different water contents. The crystal structures of both minerals have been solved using data from low-dose electron diffraction tomography combined with synchrotron powder X-ray diffraction. One of the minerals has the same powder X-ray diffraction pattern (PXRD) as for published bulachite. It has orthorhombic symmetry, space group Pnma with unit-cell parameters a = 15.3994(3), b = 17.6598(3), c = 7.8083(1) Å and Z = 4, with the formula [Al6(AsO4)3(OH)9(H2O)4]⋅2H2O. The second mineral is a higher hydrate with composition [Al6(AsO4)3(OH)9(H2O)4]⋅8H2O. It has the same Pnma space group and unit-cell parameters a = 19.855(4), b = 17.6933(11) and c = 7.7799(5) Å i.e. almost the same b and c parameters but a much larger a parameter. The structures are based on polyhedral layers, parallel to (100), of composition [Al6(AsO4)3(OH)9(H2O)4] and with H-bonded H2O between the layers. The layers contain [001] spiral chains of edge-shared octahedra, decorated with corner connected AsO4 tetrahedra that are the same as in the mineral liskeardite. The spiral chains are joined together by octahedral edge-sharing to form layers parallel to (100). Synchrotron PXRD patterns collected at different temperatures during heating of the specimen show that the higher-hydrate mineral starts transforming to bulachite when heated to 50°C, and the transformation is complete between 75 and 100°C.

Keywords

bulachiteCap Garonnenew mineralcrystal structurehydrated aluminium arsenateelectron diffractionsynchrotron powder XRD
Type
Article
Information
Mineralogical Magazine , Volume 84 , Issue 4 , August 2020 , pp. 608 - 615
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2020

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Footnotes

Associate Editor: Giancarlo Della Ventura

References

Burla, M.C., Caliandro, R., Carrozzini, B., Cascarano, G.L., Cuocci, C., Giacovazzo, C., Mallamo, M., Mazzone, A. and Polidori, G. (2015) Crystal structure determination and refinement via SIR2014. Journal of Applied Crystallography, 48, 306─309.CrossRefGoogle Scholar
Egami, T. and Billinge, S.J.L. (2003) Underneath the Bragg Peaks. Pergamon, London.CrossRefGoogle Scholar
Farrow, C.L., Juhás, P., Liu, J.W., Bryndin, D., Božin, E.S., Bloch, J., Proffen, Th. and Billinge, S.J.L. (2007) PDFfit2 and PDFgui: computer programs for studying nanostructure in crystals. Journal of Physics: Condensed Matter, 19, 335219.Google ScholarPubMed
Favreau, G. and Galea-Clolus, V. (2014) Cap Garonne. Association Française de Microminéralogie, Carry-le-Rouet, France.Google Scholar
Frau, F. and Da Pelo, S. (2001) Bulachite, a rare aluminium arsenate from Sardinia, Italy: the second world occurrence. Neues Jahrbuch für Mineralogie, Monatshafte, 2001, 18─26.Google Scholar
Gagné, O.C. and Hawthorne, F.C. (2015) Comprehensive derivation of bond-valence parameters for ion pairs involving oxygen. Acta Crystallographica, B71, 562–578.Google Scholar
Grey, I.E., Mumme, W.G., MacRae, C.M., Caradoc-Davies., T., Price, J.R., Rumsey, M.S. and Mills, S.J. (2013) Chiral edge-shared octahedral chains in liskeardite, [(Al,Fe)32(AsO4)18(OH)42(H2O)22]⋅52H2O, an open framework mineral with a pharmacoalumite-related structure. Mineralogical Magazine, 77, 3125–3135.CrossRefGoogle Scholar
Grey, I.E., Mumme, W.G., Price, J.R., Mills, S.J., MacRae, C.M. and Favreau, G. (2014) Ba−Cu ordering in bariopharmacoalumite-Q2a2b2c from Cap Garonne, France. Mineralogical Magazine, 78, 851–860.CrossRefGoogle Scholar
Grey, I.E., Kampf, A.R., Price, J.R. and MacRae, C.M. (2015) Bettertonite, [Al6(AsO4)3(OH)9(H2O)5]⋅11H2O, a new mineral from the Penberthy Croft mine, St. Hilary, Cornwall, UK, with a structure based on polyoxometalate clusters. Mineralogical Magazine, 79, 1849–1858.CrossRefGoogle Scholar
Grey, I.E., Betterton, J., Kampf, A.R., MacRae, C.M., Shanks, F.L. and Price, J.R. (2016a) Penberthycroftite, [Al6(AsO4)3(OH)9(H2O)5]⋅8H2O, a second new hydrated aluminium arsenate minerals from the Penberthy Croft mine, St. Hilary, Cornwall, UK. Mineralogical Magazine, 80, 1149–1160.CrossRefGoogle Scholar
Grey, I.E., Brand, H.E.A. and Betterton, J. (2016b) Dehydration phase transitions in new aluminium arsenate minerals from the Penberthy Croft mine, Cornwall, UK. Mineralogical Magazine, 80, 1205─1217.CrossRefGoogle Scholar
Kodjikian, S. and Klein, H. (2019) Low-dose electron diffraction tomography (LD-EDT)*. Ultramicroscopy, 200, 12─19.CrossRefGoogle ScholarPubMed
Palatinus, L., Brazda, P., Jelinek, M., Hrda, J., Steciuk, G. and Klementova, M. (2019) Specifics of the data processing of precession electron diffraction tomography data and their implementation in the program PETS2.0. Acta Crystallographica, B75, 512–522.Google Scholar
Petříček, V., Dušek, M., and Palatinus, L. (2014) Crystallographic Computing System JANA2006: General features. Zeitschrift für Kristalloraphie, 229, 345–352.Google Scholar
Schmitt, B., Bronnimann, C., Eikenberry, E.F., Gozzo, F., Hormann, C., Horisberger, R. and Patterson, B. (2003) Mythen detector system. Nuclear Instruments and Methods in Physics Research, A501, 267–272.CrossRefGoogle Scholar
Walenta, K. (1983) Bulachit, ein neues Aluminiumarsenatmineral von Neubulach im nördlichen Schwarzwald. Aufschluss, 34, 445–451.Google Scholar
Wallwork, K.S., Kennedy, B.J. and Wang, D. (2007) The high resolution powder diffraction beamline for the Australian Synchrotron, AIP Conference Proceedings, 879, 879–882.CrossRefGoogle Scholar
Supplementary material: File

Grey et al. supplementary material

Grey et al. supplementary material

Download Grey et al. supplementary material(File)
File 176.8 KB