Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-27T02:30:27.129Z Has data issue: false hasContentIssue false
  • English
  • Français

Hansblockite, (Cu,Hg)(Bi,Pb)Se2, the monoclinic polymorph of grundmannite: a new mineral from the Se mineralization at El Dragón (Bolivia)

Published online by Cambridge University Press:  02 January 2018

Hans-Jürgen Förster ,
Luca Bindi ,
Chris J. Stanley  and
Günter Grundmann
Hans-Jürgen Förster*
Affiliation:
Helmholtz Centre Potsdam German Research Centre for Geosciences GFZ, D-14473 Potsdam, Germany
Luca Bindi
Affiliation:
Dipartimento di Scienze della Terra, Università degli Studi di Firenze, Via G. La Pira 4, I-50121 Firenze, Italy
Chris J. Stanley
Affiliation:
Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
Günter Grundmann
Affiliation:
Eschenweg 6, D-32760 Detmold, Germany
*
*E-mail: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

Hansblockite, ideally (Cu,Hg)(Bi,Pb)Se2, is a new selenide from the El Dragón mine, Bolivia. It typically occurs in thin subparallel plates intergrown with two unnamed Cu–Hg–Pb–Bi–Se species, clausthalite, Corich penroseite and petrovicite.It also forms subhedral to anhedral grains up to 150 μm long and 50 μm wide. Hansblockite is non-fluorescent, black and opaque with a metallic lustre and black streak. It is brittle, with an irregular fracture and no obvious parting and cleavage. The VHN20 values range from37 to 50 (mean 42) kg mm–2 (Mohs hardness 2–2½). In plane-polarized incident light, hansblockite is cream to light grey in colour, weakly bireflectant and weakly pleochroic from greyish cream to cream. Under crossed polars, hansblockite is weakly anisotropic withkhaki to pale blue rotation tints. The reflectance values in air for the Commission on Ore Mineralogy (COM) standard wavelengths are: 47.3–48.1 (470 nm), 47.4–49.9 (546 nm), 47.1–49.0 (589 nm) and 46.6–48.5 (650 nm). The mean composition is Cu 9.31, Ag 0.73, Hg 11.43,Pb 3.55, Ni 0.17, Co 0.03, Bi 31.17, Se 34.00, total 100.39 wt.%. The mean empirical formula (based on 4 apfu) is (Cu0.68Hg0.27Ag0.03Ni0.01)∑=0.99(Bi0.69Pb0.31)∑=1.00Se2.01. The simplifiedformula is (Cu,Hg) (Bi,Pb)Se2. Hansblockite is monoclinic, space group P21/c, with a = 6.853(1), b = 7.635(1), c = 7.264(1) Å, β = 97.68(1)°, V = 376.66(9) Å3 and Z = 4. Density is 8.26 gcm–3. The five strongest powder X-ray diffraction lines [d in Å (I/I0) (hkl)] are: 3.97 (90) (111), 3.100 (40) (121), 2.986 (100) (211), 2.808 (50) (112) and 2.620 (50) (022). Hansblockite represents the monoclinic polymorph ofgrundmannite, CuBiSe2, with Hg and Pb being essential in stabilizing the monoclinic structure via the coupled substitution Cu+ + Bi3+⇔ Hg2+ + Pb2+. The mineral name is in honour of Hans Block (1881–1953), in recognition of hisimportant role in boosting Bolivian ore mining.

Keywords

hansblockitenew mineral specieschemical compositioncrystal structureseleniumEl DragónBolivia
Type
Research Article
Information
Mineralogical Magazine , Volume 81 , Issue 3 , June 2017 , pp. 629 - 640
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2017

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.)

References

Armstrong, J.T. (1995) CITZAF: a package of correction programs for the quantitative electron microbeam X-ray-analysis of thick polished materials, thin films, and particles. Microbeam Analysis, 4, 177–200.Google Scholar
Bannister, F.A. and Hey, M.H. (1937) The identity of penroseite and blockite. American Mineralogist, 22, 319–324.Google Scholar
Block, H. (1937) Das Selenvorkommen von Pacajake in Bolivien. Erzmetall, 34, 237–238.Google Scholar
Block, H. and Ahlfeld, F. (1937) Die Selenlagerstätte Pacajake, Bolivia. Zeitschrift fürpraktische Geologie, 45, 9–14.Google Scholar
Förster, H.-J., Bindi, L. and Stanley, C.J. (2016) Grundmannite, CuBiSe2, the Se-analogue of emplec-tite: a new mineral from the El Dragόn mine, Potosí, Bolivia. European Journal of Mineralogy, 28, 467–477.CrossRefGoogle Scholar
Grundmann, G., Lehrberger, G. and Schnorrer-Köhler, G. (1990) The El Dragόn mine, Potosí, Bolivia. MineralogicalRecord, 21, 133–146.Google Scholar
Herzenberg, R. and Ahlfeld, F. (1935) Blockit, ein neues Selenerz aus Bolivien. Zentralblatt für Mineralogie, Geologie und Paläontologie (Abteilung A), 9, 277–279.Google Scholar
Holland, T.J.B. and Redfern, S.A.T (1997) UNITCELL: a nonlinear least-squares program for cell-parameter refinement and implementing regression and deletion diagnostics. Journal of Applied Crystallography, 30, 84–84.CrossRefGoogle Scholar
Ibers, I A. and Hamilton, W.C. (Editors) (1974) International Tables for X-ray Crystallography, vol. IV, 366p. Kynock, Dordrecht, The Netherlands.Google Scholar
Ijjaali, I., Mitchell, K. and Ibers, I A. (2004) Preparation and structure of the light rare-earth copper selenides LnCuSe2 (Ln = La, Ce, Pr, Nd, Sm). Journal of Solid State Chemistry, 177, 760–764.CrossRefGoogle Scholar
Kampf, A.R., Mills, S.J., Nash, B.P., Thorne, B. and Favreau, G. (2016) Alfredopetrovite: a new selenite mineral from the El Dragόn mine. European Journal of Mineralogy, 28, 479–484.CrossRefGoogle Scholar
Mills, S.J., Kampf, A.R., Christy, A.G., Housley, R.M., Thorne, B., Chen, Yu-Sheng and Steele, I.M. (2014) Favreauite, a new selenite mineral from the El Dragόn mine, Bolivia. European Journal of Mineralogy, 26, 771–781.CrossRefGoogle Scholar
Oxford Diffraction (2006) CrysAlis RED (Version 1.171.31.2) and ABSPACK in CrysAlis RED. Oxford Diffraction Ltd, Abingdon, Oxfordshire, England.Google Scholar
Paar, W.H., Cooper, M.A., Moёlo, Y., Stanley, C.J., Putz, H., Topa, D., Roberts, A.C., Stirling, J., Raith, J.G. and Rowe, R. (2012) Eldragόnite, Cu6BiSe4(Se)2, a new mineral species from the El Dragόn mine, Potosí, Bolivia, and its crystal structure. The Canadian Mineralogist, 50, 281–294.CrossRefGoogle Scholar
Sheldrick, G.M. (2008) A short history of SHELX. Acta Crystallografica, A64, 112–122.CrossRefGoogle Scholar
Simon, G. and Essene, E.J. (1996) Phase relations among selenides, sulphides, tellurides, and oxides: I. Thermodynamic properties and calculated equilibria. Economic Geology, 91, 1183–1208.CrossRefGoogle Scholar
Simon, G. and Essene, E.J. (1997) Phase relations among selenides, sulphides, tellurides, and oxides: II: Applications to selenide-bearing ore deposits. Economic Geology, 92, 468–484.CrossRefGoogle Scholar
Wiegers, G.A. (1971) The crystal structure of the low-temperature form of silver selenide. American Mineralogist, 56, 1882–1888 Google Scholar
Supplementary material: File

Förster et al. supplementary material

Structure factors and crystallographic information file

Download Förster et al. supplementary material(File)
File 105.6 KB