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Herbertsmithite, Cu3Zn(OH)6Cl2, a new species, and the definition of paratacamite

Published online by Cambridge University Press:  05 July 2018

R. S. W. Braithwaite ,
K. Mereiter ,
W. H. Paar  and
A. M. Clark
R. S. W. Braithwaite
Affiliation:
Chemistry Department, University of Manchester Institute of Science and Technology, Manchester M60 1QD, UK
K. Mereiter
Affiliation:
Institut für Mineralogie, Kristallographie und Strukturchemie der Technischen Universität Wien, Getriedemarkt 9, A-1060 Wien, Austria
W. H. Paar*
Affiliation:
Department Geography, Geology and Mineralogy, Division Mineralogy and Material Sciences, Universität Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
A. M. Clark
Affiliation:
Mineralogy Department, The Natural History Museum, Cromwell Road, London SW7 5BD, UK
*
*E-mail: werner.paar@sbg.ac.at
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Abstract

One in four of the Cu-filled cation sites in clinoatacamite, the monoclinic polymorph of atacamite and botallackite, is angle- rather than Jahn-Teller-distorted. Experiments show that this site alone is susceptible to substitution by a non-Jahn-Teller distorting cation of suitable radius and charge, such as Zn2+, and also Ni2+, Co2+, Fe2+, Cd2+ and Mg2+. The crystal symmetry changes to rhombohedral when ∼⅓ of the Cu in this site is substituted by e.g. Zn, thus giving paratacamite; the Zn is essential for stability and forms, with larger proportions of Zn, a series to the end-member in which the site is fully occupied by Zn. This end-member, rhombohedral stoichiometric Cu3Zn(OH)6Cl2, has been characterized using natural specimens from Chile and Iran and is named herbertsmithite. The other cations mentioned behave similarly, producing stabilized rhombohedral paratacamites and end-members analogous to herbertsmithite, which if found in nature, as the Ni analogue has been, should be named species. Clinoatacamite, paratacamite and herbertsmithite have rather similar X-ray powder diffraction patterns, but are readily distinguished by infrared spectroscopy.

Zn-stabilized paratacamite forms blue-green crystals of rhombohedral habit, with vitreous lustre, e = 1.828-1.830, o = 1.835, uniaxial negative, weakly pleochroic O > E, density: 3.75 g cm-3, Mohs hardness: 3-3½; space group R, a = 13.654(5), c = 14.041(6) Å, Z = 24, with pronounced Rm substructure; six strongest XRD lines 5.452 (100), 2.895 (20), 2.760 (74), 2.262 (52), 1.817 (18), 1.708 (21).

Herbertsmithite forms dark green crystals of rhombohedral habit, with vitreous lustre, e = 1.817, o = 1.825, uniaxial negative, weakly pleochroic O > E, density: 3.95 g cm-3, Mohs hardness: 3-3½;; space group Rm with no superstructure observed, a = 6.834(1), c = 14.075(2) Å, Z = 3; six strongest XRD lines 5.466 (55), 4.702 (14), 2.764 (100), 2.266 (36), 1.820 (13), 1.709 (18).

Keywords

herbertsmithiteparatacamiteanarakitesolid solutionsite occupancy and selectivitynew mineralIR spectroscopyXRDCu chloridesAnarakIranSierra GordaChile
Type
Research Article
Information
Mineralogical Magazine , Volume 68 , Issue 3 , June 2004 , pp. 527 - 539
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2004

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References

Adib, D. (1972) Mineralogische Untersuchungen in der Oxydationszone der Lagerstä tte Tschah-Khuni, Anarak, Zentral-Iran. Inaugural-Dissertation for Doctorate, Ruprecht-Karl-Universität, Heidelberg, Germany.Google Scholar
Adib, D. and Ottemann, J. (1972) Ein neues Mineral, (Cu,Zn)2(OH)3Cl, aus der Kali-Kafi Mine, Provinz Anarak, Zentral Iran. Neues Jahrbuch für Mineralogie, Monatshefte, 335–338 (abstracted with comments, in American Mineralogist (1973), 58, 560–561.).Google Scholar
Aebi, F. (1948) The crystal structure of basic copper bromide CuBr2.3Cu(OH)2 . Helvetica Chimica Acta, 31, 369–378.CrossRefGoogle ScholarPubMed
Embrey, P.G. and Jones, G. (1981) Personal communication, in Kracher and Pertlik (1983).Google Scholar
Feitknecht, W. and Maget, K. (1949a) Zur Chemie und Morphologie der basischen Salze zweiwertiger Metalle, XIV, Die Hydroxychloride des Kupfers. Helvetica Chimica Acta, 32, 1639–1653.CrossRefGoogle Scholar
Feitknecht, W. and Maget, K. (1949b) Über Doppelhydroxide und basische Doppelsalze: Über basische Doppelchloride des Kupfers. Helvetica Chimica Acta, 32, 1653–67.CrossRefGoogle Scholar
Fleet, M.E. (1975) The crystal structure of paratacamite, Cu2(OH)3Cl. Acta Crystallographica, B31, 183–187.CrossRefGoogle Scholar
Frondel, C. (1950) On paratacamite and some related copper chlorides. Mineralogical Magazine, 29, 34–45.CrossRefGoogle Scholar
Garrels, R.M. and Stine, L.O. (1948) Replacement of calcite by atacamite in copper chloride solutions. Economic Geology, 43, 21.CrossRefGoogle Scholar
Grice, J.D., Szymanski, J.T. and Jambor, J.L. (1996) The crystal structure of clinoatacamite, a new polymorph of Cu2(OH)3Cl. The Canadian Mineralogist, 34, 73–8.Google Scholar
Jambor, J.L., Dutrizac, J.E., Roberts, A.C., Grice, J.D. and Szymanski, J.T. (1996) Clinoatacamite, a new polymorph of Cu2(OH)3Cl, and its relationshipto paratacamite and “anarakite”. The Canadian Mineralogist, 34, 61–72.Google Scholar
Kracher, A. and Pertlik, F. (1983) Zinkreicher Paratacamit, Cu3Zn(OH)6Cl2, aus der Herminia Mine, Sierra Gorda, Chile. Annalen des Naturhistorischen Museum Wien, 85/A, 93–7.Google Scholar
Martinez, O.G., Cano-Ruiz, J. and Gutierrez Rios, E. (1966) Hidroxisales: IV Constitución quimica de Los hidroxicloruros dobles de cationes bivalentes. Anales Real Sociedad Española Fisica y Quimica (Madrid), 62, Series B, 51–62.Google Scholar
Nickel, E.H., Clout, J.F.M. and Gartrell, B.J. (1994) Secondary nickel minerals from Widgiemooltha, Western Australia. Mineralogical Record, 25, 283–291, 302.Google Scholar
Oswald, H.R. and Feitknecht, W. (1964) Über die Hydroxidhalogenide Me2(OH)3Cl, -Br, -J zweiwertiger Metalle (Me = Mg, Ni, Co, Cu, Fe, Mn). Helvetica Chimica Acta, 47, 272–289.CrossRefGoogle Scholar
Oswald, H.R. and Guenter, J.R. (1971) Crystal data on paratacamite g-Cu2(OH)3Cl. Journal of Applied Crystallography, 4, 530–1CrossRefGoogle Scholar
Pollard, A.M., Thomas, R.G. and Williams, P.A. (1989) Synthesis and stabilities of the basic copper(II) chlorides atacamite, paratacamite and botallackite. Mineralogical Magazine, 53, 557–563.CrossRefGoogle Scholar
Pring, A., Snow, M.R. and Tiekink, E.R.T. (1987) Paratacamite from South Australia. Transactions of the Royal Society of South Australia, 3, 127–128.Google Scholar
Sharkey, J.B. and Lewin, S.Z. (1971) Conditions governing the formation of atacamite and paratacamite. American Mineralogist, 56, 179–192.Google Scholar
Smith, G.F.H. (1906) Paratacamite, a new oxychloride of copper. Mineralogical Magazine, 14, 170–177.CrossRefGoogle Scholar
Tennent, N.H. and Antonio, K.M. (1981) ICOM Committee for Conservation. 6th. Triennial Meeting, Ottawa. Paper 81/23/3.Google Scholar
Walter-Levy, L. and Goreaud, M. (1969) Sur la formation des chlorures basiques cuivriques en solution aqueuse de 25 à 200°C. Bulletin de la Societe Chimique de France, 1969, 2623–2634.Google Scholar
Wolff, P.M. de (1953) Crystal structure of Co2(OH)3Cl. Acta Crystallographica, 6, 359–360.CrossRefGoogle Scholar