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On the symmetry of tsumcorite group minerals based on the new species rappoldite and zincgartrellite

Published online by Cambridge University Press:  05 July 2018

H. Effenberger ,
W. Krause ,
H.-J. Bernhardt  and
M. Martin
H. Effenberger*
Affiliation:
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraβe 14, A-1090 Vienna, Austria
W. Krause
Affiliation:
Henriette-Lott-Weg 8, D-50354 Hürth, Germany
H.-J. Bernhardt
Affiliation:
Ruhr-Universität Bochum, Institut für Mineralogie, Universitätsstraûe 150, D-44780 Bochum, Germany
M. Martin
Affiliation:
Heinrich-Zille-Weg 8, D-09599 Freiberg, Germany
*
*E-mail: [email protected]
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Abstract

Rappoldite, the Co-analogue of helmutwinklerite, and zincgartrellite, the Zn-dominant analogue of gartrellite, are two new members of the tsumcorite group. Both minerals are triclinic, their structures are closely related to the parent structure, i.e. the ‘tsumcorite type’ (C2/m, Z = 2). The lower symmetry is caused by two different crystal-chemical requirements. Order phenomena of the hydrogen bonds cause the ‘helmutwinklerite type’ (P1̄, Z= 4), ordering of Cu2+and Fe3+ is responsible for the ‘gartrellite type’ (P1̄, Z = 1).

Rappoldite was found on samples from the Rappold mine near Schneeberg, Saxony, Germany. The new species forms red to red-brown prismatic and tabular crystals up to 1 mm long. Dcalc. = 5.28 g/cm3. 2Vz = 85(5)°, nx = 1.85 (calc.), ny = 1.87(2) and nz = 1.90(2); dispersion is distinct with r > v; orientation is Y ∼∥ [1̄ 20] and X ∼ ∥ c. The empirical formula derived from electron microprobe analyses is (Pb1.01Ca0.01)Σ1.02(Co0.99Ni0.62Zn0.35Fe0.02)Σ1.98[(AsO4)1.99(SO4)0.01]Σ2.00[(OH)0.02(H2O)1.98]Σ2.00 or Pb(Co,Ni)2(AsO4)2·2H2O. Single-crystal X-ray studies showed average C2/m symmetry. Weak superstructure reflections are responsible for triclinic symmetry and enlarged cell metrics (refined from powder data): a= 11.190(2)Å, b= 10.548(2)Å, c= 7.593(1)Å, α = 100.38(1)8, β = 109.59(2)8, γ = 98.96(1)8, V= 807.6 Å3, Z= 4. The superstructure results from the hydrogen-bond scheme, but faint streaks indicate some disorder. All investigated rappoldite crystals are twinned by reflection on (23̄0) which corresponds to the mirror plane of the average C2/m cell. Helmutwinklerite is isotypic with rappoldite and probably also with pure thometzekite; sulphatian thometzekite is monoclinic.

Zincgartrellite forms green-yellow rosette-like aggregates on samples from the Tsumeb mine, Namibia. The Dcalc. = 5.30 g/cm3. 2Vx = 87(5)°, nx = 1.91(2), ny = 1.94 (calc.) and nz = 1.97(2). Electron-microprobe analyses and Mössbauer data yielded the empirical formula (Pb0.97Ca0.04)Σ1.01(Zn0.91Cu0.51Fe0.59Al0.03)Σ2.04[(AsO4)1.96(SO4)0.01]Σ1.97[(OH)0.81(H2O)1.31]Σ2.12 or Pb(Zn,Fe,Cu)2(AsO4)2(H2O,OH)2. The structural formula is Pb(ZnxFe1–x)(ZnxCu1–x)(AsO4)2(OH)1–x(H2O)1+xwith 0.4 < x < 0.8. Gartrellite is defined by x < 0.4. Helmutwinklerite has x near to 1 and is defined by a cell with fourfold volume. Single-crystal X-ray studies of zincgartrellite proved space group P1̄ caused by ordering of Fe3+ and Cu at one atomic site. Cell parameters (refined from powder data): a= 5.550(1)Å, b= 5.620(1)Å, c= 7.621(1)Å, α = 68.59(1), β = 69.17(1), γ = 69.51(1)°, V= 200.1 Å3, Z= 1.

Keywords

tsumcorite group mineralsrappolditezincgartrellitehelmutwinkleritegartrellitethometzekitecrystal symmetrycrystal chemistrycrystal structureinfrared spectra
Type
Research Article
Information
Mineralogical Magazine , Volume 64 , Issue 6 , December 2000 , pp. 1109 - 1126
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2000

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References

Beran, A., Giester, G. and Libowitzky, E. (1997) The hydrogen bond system in natrochalcite-type compounds – an FTIR spectroscopic study of the H3O2 – unit. Mineral. Petrolog., 61, 223–35.CrossRefGoogle Scholar
Fischer, R.X. and Tillmanns, E. (1988) The equivalent isotropic displacement factor. Acta Crystallogr., C44, 775–6.Google Scholar
Kharisun, , Taylor, M.R., Bevan, D.J.M., Rae, A.D. and Pring, A. (1997) The crystal structure of mawbyite, PbFe2(AsO4)2(OH)2 . Mineral. Mag., 61, 685–91.CrossRefGoogle Scholar
Kharisun, , Taylor, M.R., Bevan, D.J.M. and Pring, A. (1998) The crystal chemistry of duftite, PbCuAsO4(OH) and the β-duftit e problem. Mineral. Mag., 62, 121–30.CrossRefGoogle Scholar
Krause, W., Belendorff, K., Bernhardt, H.-J., McCammon, C., Effenberger, H. and Mikenda, W. (1998 a) Crystal chemistry of the tsumcorite-group minerals. New data on ferrilotharmeyerite, tsumcorite, thometzekite, mounanaite, helmutwinklerite, and a redefinition of gartrellite. Eur. J. Mineral., 10, 179-206.CrossRefGoogle Scholar
Krause, W., Belendorff, K., Bernhardt, H.-J. and Petitjean, K. (1998 b) Phosphogartrellite, PbCuFe(PO4)2(OH)·H2O, a new member of the tsumcorite group. Neues Jahrb. Mineral. Mh., 111–8.Google Scholar
Krause, W., Bernhardt, H.-J. and Effenberger, H. (1999 a) Symmetry of tsumcorite-group minerals. Berichte der Deutschen Mineral. Ges., Beih. z. Eur. J. Mineral., 11(1), 136.Google Scholar
Krause, W., Effenberger, H., Bernhardt, H.-J. and Martin, M. (1999 b) Cobaltlotha rmeyeri te, Ca(Co,Fe,Ni)2(AsO4)2(OH,H2O)2, a new mineral from Schneeberg, Germany. Neues Jahrb. Mineral. Mh., 505–17.Google Scholar
Martin, M. and Schlegel, F. (1992) Kobaltaustinit und Tsumcor it von der Rappold-Fundgrube in Schneeberg/Sachsen. Lapis, 17, 28–9.Google Scholar
Pring, A., McBriar, E.M. and Birch, W.D. (1989) Mawbyite, a new arsenate of lead and iron related to tsumcorite and carminite, from Broken Hill, New South Wales. Amer. Mineral., 74, 1377–81.Google Scholar
Schmetzer, K., Nuber, B. and Medenbach, O. (1985) Thometzekite, a new mineral from Tsumeb, Namibia, and symmetry relations in the tsumcorite-helmutwinklerite family. Neues Jahrb. Mineral. Mh., 446 52.Google Scholar
Shannon, R.D. (1976) Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Crystallogr., A32, 751–67.CrossRefGoogle Scholar
Sheldrick, G.M. (1976) SHELX-76 Programs for Crystal Structure Determination. Univ. Cambridge, UK.Google Scholar
Sheldrick, G.M. (1997) SHELXL-97 Program for Crystal Structure Refinement. Univ. Göttingen, Germany.Google Scholar
Süsse, P. and Schnorrer, G. (1980) Helmutwinklerite, a new arsenate mineral from Tsumeb, S.W. Africa. Neues Jahrb. Mineral. Mh., 118–24.Google Scholar
Tillmanns, E. and Gebert, W. (1973) The crystal structure of tsumcorite, a new mineral from the Tsumeb Mine, S.W. Africa. Acta Crystallogr., B29, 2789–94.CrossRefGoogle Scholar
Wilson, A.J.C. (editor) (1992) International Tables for Crystallography, Vol. C. Kluwer, Dordrecht, The Netherlands.Google Scholar
Yvon, K., Jeitschko, W., and Parthé, E. (1977) LAZY PULVERIX, a computer program for calculating X-ray and neutron powder patterns. J. Appl. Crystallogr., 10, 73–4.CrossRefGoogle Scholar