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Lead-bearing phyllotungstite from the Clara mine, Germany with an ordered pyrochlore–hexagonal tungsten bronze intergrowth structure

  • I. E. Grey (a1), W. G. Mumme (a1) and C. M. MacRae (a1)


Lead-bearing phyllotungstite from the Clara mine in the central Black Forest, Germany has a formula (Cs0.41)Na0.14K0.05Pb2+ 2.01Ca0.26[W6+ 10.87Fe3+ 3.13O35.75(OH)6.25](O(H2O)3). X-ray diffraction patterns exhibit pseudohexagonal symmetry, but refinement of single-crystal synchrotron data has shown that the true symmetry is orthorhombic, Cmcm, with a = 7.298(1), b = 12.640(2), c = 19.582(4) Å, and that the pseudohexagonal character is due to submicrometre-scale cyclical twinning by rotation about the pseudohexagonal c axis. The structure can be described in terms of an ordered intergrowth, parallel to (001), of (111)py blocks with pyrochlore-type structures, which are ~6 Å in width, and two-layer wide regions with a hexagonal tungsten bronze (HTB) type structure. Caesium atoms occupy 18-coordinate cavities in the HTB regions, and H2O molecules occupy Φ sites in the A 2 B 2O6Φ pyrochlore blocks. The lowering of symmetry from hexagonal to orthorhombic is due to partial ordering of W and Fe in the octahedral B sites and of Pb and vacancies in the A sites of the pyrochlore blocks. The ideal formula for the intergrowth structure (with no vacancies) is C 2A10[B14(O,OH)424, where C is the cavity site in the HTB slabs. The mineral has only 21% occupancy of the C site and 25% occupancy of the A site, but full occupancy of the Φ site. There may be some mixing of Cs and H2O between the C and Φ sites.


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Andersson, S. and Hyde, B.G. (1974) Twinning at the unit cell level as a structure-building operation in the solid state. Journal of Solid State Chemistry, 9, 92–101.
Armstrong, J.T. (1988) Quantitative analysis of silicate and oxide materials: comparison of Monte Carlo, ZAF and j(rZ) procedures. Pp. 239–246. in: Microbeam Analysis (D.E. Newbury, editor). San Francisco Press, San Francisco, California, USA.
Atencio, D., Andrade, M.B., Christy, A.G., Gieré, R. and Kartashov, P.M. (2010) The pyrochlore supergroup of minerals: nomenclature. The Canadian Mineralogist, 48, 673–698.
Beyerlein, R.A., Horowitz, H.S., Longo, J.M., Jorgensen, J.D. and Rotella, F.J. (1984) Neutron diffraction investigation of ordered oxygen vacancies in the defect pyrochlores, Pb2Ru2O6.5 and PBTlNb2O6.5 . Journal of Solid State Chemistry, 51, 253–265.
Birch, W.D., Grey, I.E., Mills, S.J., Bougerol, C., Pring, A. and Ansermet, S. (2007) Pittongite, a new tungstate with a mixed-layer, pyrochlore–hexagonal agonal tungsten bronze structure, from Victoria, Australia. The Canadian Mineralogist, 45, 857–864.
Brese, N.E. and O’Keeffe, M. (1991) Bond-valence parameters for solids. Acta Crystallographica, B47, 192–197.
Brusetti, R., Bordet, P. and Marcus, J. (2003) Investigation of the Rb–W–O system in connexion with the superconducting properties of the hexagonal tungsten bronzes. Journal of Solid State Chemistry, 172, 148–159.
Cole, H., Chambers, F.W. and Dunn, H.M. (1962) Simultaneous diffraction: indexing Umweganregung peaks in simple cases. Acta Crystallographica, 15, 138–144.
Ercit, T.S. and Robinson, G.W. (1994) A refinement of the structure of ferritungstite from Kalzas Mountain, Yukon, and observations on the tungsten pyrochlores. The Canadian Mineralogist, 32, 567–574.
Ercit, T.S., Č erný , P. and Hawthorne, F.C. (1993) Cesstibtantite – a geologic introduction to the inverse pyrochlores. Mineralogy and Petrology, 48, 235–255.
Ercit, T.S., Hawthorne, F.C. and Č erný , P. (1994) The structural chemistry of kalipyrochlore, a “hydropyrochlore”. The Canadian Mineralogist, 32, 415–420.
Farrugia, L.J. (1999) WinGX suite for small-molecule single-crystal crystallography. Journal of Applied Crystallography, 32, 837–838.
Goreaud, M. and Raveau, B. (1980) Alunite and crandallite: a structure derived from that of pyrochlore. American Mineralogist, 65, 953–956.
Grey, I.E., Birch, W.D., Bougerol, C. and Mills, S.J. (2006) Unit-cell intergrowth of pyrochlore and hexagonal tungsten bronze structures in secondary tungsten minerals. Journal of Solid State Chemistry, 179, 3860–3869.
Grey, I.E., Mumme, W.G., Vanderah, T.A., Roth, R.S. and Bougerol, C. (2007) Chemical twinning of the pyro chlorestructure in the system Bi2O3–Fe2O3–Nb2O5 . Journal of Solid State Chemistry, 180, 158–166.
Grey, I.E., Vanderah, T.A., Mumme, W.G., Roth, R.S., Guzman, J., Nino, J.C. and Levin, I. (2008a) Crystal structure, stoichiometry, and dielectric relaxation in Bi3.32Nb7.09O22.7 and structurally related ternary phases. Journal of Solid State Chemistry, 181, 499–507.
Grey, I.E., Mumme, W.G., Bordet, P. and Mills, S.J. (2008b) A new crystal-chemical variation of the alunite-type structure in monoclinic PbZn0.5Fe3(AsO4)2(OH)6 . The Canadian Mineralogist, 46, 1577–1586.
Grey, I.E., Scarlett, N.V.Y., Bordet, P. and Brand, H.E.A. (2011) Jarosite–butlerite intergrowths in non-stoichiometric jarosites: crystal chemistry of monoclinic natrojarosite–hydroniumjarosite phases. Mineralogical Magazine, 75, 2775–2791.
Griffith, C.S., Luca, V., Hanna, J.V., Pike, K.J., Smith, M.E. and Thorogood, G.S. (2009) Microcrystalline hexagonal tungsten bronze. 1. Basis of ion exchange selectivity for cesium and strontium. Inorganic Chemistry, 48, 5648–5662.
Groult, D., Pannetier, J. and Raveau, B. (1982) Neutron diffraction study of the defect pyrochlores TaWO5.5, HTaWO6, H2Ta2O6 and HTaWO6·H2O. Journal of Solid State Chemistry, 41, 277–285.
Günter, J.R., Amberg, M. and Schmalle, H. (1989) Direct synthesis and single crystal structure determination of cubic pyrochlore-type tungsten trioxide hemihydrates, WO3·0.5H2O. Materials Research Bulletin, 24, 289–292.
Hamilton, W.C. (1965) Significance tests on the crystallographic R factor. Acta Crystallographica, 18, 502–510.
Hartung, A. von, Verscharen, W., Binder, F. and Babel, D. (1979) Die pseudohexagonale Wolframbronzestruktur der monoklinen Phase Cs0.4Zn0.4Fe1.6F6 und verwandter Cä sium-U¨ bergangsmetallfluoride. Zeitschrift für Anorganische Allgemeine Chemie, 456, 106–116.
Kihlborg, L. and Sundberg, M. (1997) “Inverted twinning” in intergrowth tungsten bronzes. Acta Crystallographica, B53, 95–101.
Krivovichev, S.V. and Brown, I.D. (2001) Are the compressive effects of encapsulation an artefact of the bond valence parameters? Zeitschrift fü r Kristallographie, 216, 245–247.
Kudo, T., Oi, J., Kishimoto, A. and Hiratani, M. (1991) Three kinds of framework structures of cornersharing WO6 octahedra derived from peroxopolytungstates as a precursor. Materials Research Bulletin, 26, 779–787.
Leblanc, M., Ferey, G., Chevallier, P., Calage, Y. and De Pape, R. (1983) Hexagonal tungsten bronze-type FeIII fluoride: (H2O)0.33FeF3: crystal structure, magnetic properties, dehydration to a new form of iron trifluoride. Journal of Solid State Chemistry, 47, 53–58.
Magnéli, A. (1953) Studies on the hexagonal tungsten bronzes of potassium, rubidium and cesium. Acta Chemica Scandinavica, 7, 315–324.
Marsh, R.E. (1995) Some thoughts on choosing the correct space group. Acta Crystallographica, B51, 897–907.
Mills, S.J., Grey I.E., Mumme, W.G., Miyawaki, R., Matsubara, S., Bordet, P., Birch, W.D. and Raudsepp, M. (2008) Kolitschite, PbZn0.5Fe3 (AsO4)2(OH)6, a new mineral from the Kintore opencut, Broken Hill, New South Wales. Australian Journal of Mineralogy, 14, 15–19.
Oi, J., Kishimoto, A. and Kudo, T. (1993) Hexagonal and pyrochlore-type cesium tungstates synthesized from cesium peroxo-polytungstate and their redox chemistry. Journal of Solid State Chemistry, 103, 176–185.
Petříček, V. and Dušek, M. (2000): JANA2000, a Crystallographic Computing System. Institute of Physics, Academy of Sciences of the Czech Republic, Prague.
Prince, E. (1982) Comparison of the fits of two models to the same data set. Acta Crystallographica, B38, 1099–1100.
Pye, M.F. and Dickens, P.G. (1979) A structural study of the potassium tungsten bronze, K0.26WO3 . Materials Research Bulletin, 14, 1397–1402.
Thorogood, G.J., Saines, P.J., Kennedy, B.J., Withers, R.L. and Elcombe, M.M. (2008) Diffuse scattering in the cesium pyrochlore CsTi0.5W1.5O6 . Materials Research Bulletin, 43, 787–795.
Walenta, K. (1984) Phyllotungstit, ein neues sekundäres Wolframmineral aus der Grube Clara im mittleren Schwarzwald. Neues Jahrbuch für Mineralogie- Monatshafte, 1984, 529–535.
Walenta, K. and Theye, T. (2008) Pittongit und Phyllotungstit. Der Erzgräber, 20, 103–107.
Walenta, K. and Theye, T. (2010a) Ein bleireiches und ein kaliumreiches Phyllotungstitmineral von der Grube Clara im mittleren Schwarzwald. Der Erzgräber, 24, 66–76.
Walenta, K. and Theye, T. (2010b) Ein dem Phyllotungstit nahestehendes cäsiumreiches Mineral von der Grube Clara bei Oberwolfach im mittleren Schwarzwald. Der Erzgräber, 24, 1–8.


Type Description Title
Supplementary materials

Grey et al. supplementary material
CIF P63/mmc

 Unknown (45 KB)
45 KB
Supplementary materials

Grey et al. supplementary material
CIF Cmcm

 Unknown (94 KB)
94 KB

Lead-bearing phyllotungstite from the Clara mine, Germany with an ordered pyrochlore–hexagonal tungsten bronze intergrowth structure

  • I. E. Grey (a1), W. G. Mumme (a1) and C. M. MacRae (a1)


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