Hostname: page-component-77c89778f8-cnmwb Total loading time: 0 Render date: 2024-07-20T22:06:35.381Z Has data issue: false hasContentIssue false
  • English
  • Français

Redefinition of arhbarite, Cu2Mg(AsO4)(OH)3

Published online by Cambridge University Press:  05 July 2018

W. Krause ,
H.-J. Bernhardt ,
H. Effenberger ,
U. Kolitsch  and
CH. Lengauer
W. Krause*
Affiliation:
Henriette-Lott-Weg 8, D-50354 Hürth, Germany
H.-J. Bernhardt
Affiliation:
Institut für Mineralogie, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum, Germany
H. Effenberger
Affiliation:
Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, Althanstraße 14, A-1090 Wien, Austria
U. Kolitsch
Affiliation:
Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, Althanstraße 14, A-1090 Wien, Austria
CH. Lengauer
Affiliation:
Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, Althanstraße 14, A-1090 Wien, Austria
*
* E-mail: We.Krause@t-online.de
Get access Rights & Permissions [Opens in a new window]

Abstract

Arhbarite was described in 1982 as a new copper arsenate, Cu2(OH)AsO4·6H2O, from the Arhbar mine, Morocco. Due to the very small grain size no crystallographic data other than the X-ray powder diffraction data could be given. Reinvestigation of the type material and of new finds from the El Guanaco mine, Chile, is based on Rietveld refinement of X-ray powder data, electron microprobe investigations, optical studies as well as infrared and Raman spectra. The main results are: (1) arhbarite has the ideal formula Cu2Mg(AsO4)(OH)3 with magnesium oxide as an additional constituent and (2) arhbarite is isotypic with gilmarite, Cu3(AsO4)(OH)3. Arhbarite is triclinic, space group P1 (no. 1), unit-cell parameters (type material; refined from powder data) a= 5.315(4), b= 5.978(6), c= 5.030(6)Å, α = 113.58(6), β = 97.14(7), γ = 89.30(8)°, V= 145.2(1)Å3, Z= 1. Microprobe analyses of the type material gave MgO 10.20, CuO 47.46, NiO 0.20, CoO 0.24, As2O5 33.85, SiO2 0.10, H2O 7.58 (calc.), total 99.63 wt.%. The empirical formula is Cu1.98(Mg0.88Cu0.09Ni0.01Co0.01)S0.99(AsO4)1.02(OH)2.92, based on 7 O atoms. The Chilean arhbarite shows a slightly higher Cu content than the type material; it has the formula Cu1.99(Mg0.73Cu0.25Zn0.01)∑0.99[(AsO4)1.01(SiO4)0.01]∑1.02(OH)2.92. The formal redefinition of arhbarite has been approved by the CNMMN of the IMA.

Keywords

arhbariteredefinitionRietveld refinementmicroprobe datainfrared spectraRaman spectracrystal chemistrygilmarite.
Type
Research Article
Information
Mineralogical Magazine , Volume 67 , Issue 5 , October 2003 , pp. 1099 - 1107
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2003

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

Eby, R.K. and Hawthorne, F.C. (1990 Clinoclase and the geometry of [5]-coordinate Cu + in minerals. Ada Crystallographica, C46, 2291—2294.Google Scholar
Farber, G., Witzke, T., Neumeier, G. and WeiB, S. (1998 Die besten Stufen des seltenen Kupferarsenat es Arhbarit - ein sensationeller Neufund aus Chile. Lapis, 23(10, 49—51.Google Scholar
Kolitsch, U., Witzke, T. and Wiechowski, A. (2000 A new Cu-Mg-arsenate from El Guanaco, near Taltal, Chile: crystal structure and preliminary data. European Journal of Mineralogy, 12, Beih. No. 1, 102.Google Scholar
Mandarino, J.A. (1981a) The Gladstone-Dale relation-ship: part IV. The compatibility concept and its application. The Canadian Mineralogist, 19, 441—450.Google Scholar
Mandarino, J.A. (1981b) Comments on the calculation of the density of minerals. The Canadian Mineralogist, 19, 531—534.Google Scholar
Rietveld, H.M. (1969 A profile refinement method for nuclear and magnetic structures. Journal of Applied Crystallography, 2, 65—71.CrossRefGoogle Scholar
Sarp, H. and Cerny, R. (1999 Gilmarite, Cu3(AsO4)(OH)3, a new mineral: its description and crystal structure. European Journal of Mineralogy, 11, 549—555.CrossRefGoogle Scholar
Schmetzer, K., Tremmel, G. and Medenbach, O. (1982 Arhbarit, Cu2[OHIAsO4]-6H2O, ein neues Mineral von Bou-Azzer, Marokko. Neues Jahrbuch fur Mineralogie, Monatshefte, 529— 533.Google Scholar
Visser, J.W. (1969 A fully automatic program for finding the unit cell from powder data. Journal of Applied Crystallography, 2, 89—95.CrossRefGoogle Scholar
Yvon, K., Jeitschko, W. and Parthe, E. (1977 LAZY PULVERIX, a computer program, for calculating X-ray and neutron diffraction powder patterns. Journal of Applied Crystallography, 10, 73—74.CrossRefGoogle Scholar