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The chemical stability of mimetite and distribution coefficients for pyromorphite–mimetite solid-solutions

Published online by Cambridge University Press:  05 July 2018

Adedayo I. Inegbenebor ,
John H. Thomas  and
Peter A. Williams
Adedayo I. Inegbenebor
Affiliation:
Department of Chemistry, University College, P.O. Box 78, Cardiff CF1 1XL
John H. Thomas
Affiliation:
Department of Chemistry, University College, P.O. Box 78, Cardiff CF1 1XL
Peter A. Williams
Affiliation:
Department of Chemistry, University College, P.O. Box 78, Cardiff CF1 1XL
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Abstract

The equilibrium solubility of mimetite has been determined in aqueous solution at 298.2K. For the reaction Pb5(ASO4)3Cl(s,mimetite)+6H+(aq)⇌5Pb2+(aq)+3H2AsO4−(aq)+Cl−(aq) at this temperature log KH+, extrapolated to zero ionic strength, is equal to −27.9(4). This value is equal, within experimental error, to that corresponding to pyromorphite, Pb5(PO4)3Cl, derived from the literature, and redetermined here under analogous conditions. Distribution coefficients in terms of both HXO42− and H2XO4−(aq) ions (X = P,As) have also been determined for solid phases of the pyromorphite-mimetite solid solution series containing from 5 to 95 mol. % mimetite. Although the two end-members are isostructural without being strictly isomorphous, the solid solution series behaves ideally over the whole compositional range; that is, the composition of the solid phase reflects the ratio of arsenate to phosphate species in aqueous solution at pH values corresponding to naturally-occurring aqueous solutions generally associated with the oxidized zones of base metal orebodies. Some relationships between mimetite and other secondary lead(II) and copper(II) arsenate minerals have been explored.

Keywords

chemical stabilitymimetitedistribution coefficientspyromorphite-mimetitesolidsolutions
Type
Experimental Studies
Information
Mineralogical Magazine , Volume 53 , Issue 371 , June 1989 , pp. 363 - 371
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1989

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Footnotes

*

Author for correspondence

References

Baas Becking, L. G. M., Kaplan, I. R., and Moore, D. (1960) J. Geol. 68, 243-84.CrossRefGoogle Scholar
Baker, W. E. (1966) Am. Mineral. 51, 1712-21.Google Scholar
Barner, H. E., and Scheuerman, R. H. (1978) Handbook of Thermochemical Data for Compounds and Aqueous Species. John Wiley and Sons, New York.Google Scholar
Fleischer, M. (1987) Glossary of Mineral Species. 5th ed., Mineralogical Record Inc., Tucson.Google Scholar
Förtsch, E. (1970) NeuesJahrb. Mineral. Abh. 113, 219-50.Google Scholar
Garrels, R. M., and Christ, C. L. (1965) Solutions, Minerals, and Equilibria. Harper and Row, New York.Google Scholar
Keller, P. (1977) Mineral. Rec. 8, 38-47.Google Scholar
Keller, P. and Bartelke, W. (1982) Ibid. 13, 137-47.Google Scholar
Keppler, U. (1968) Neues. Jahrb. Mineral. Mh. 359-62.Google Scholar
Keppler, U. (1969) Ibid. 64-7.Google Scholar
Kharaka, Y. K., Robinson, S. W., Law, L. W., and Carothers, W. W. (1984) Geochim. Cosmochim. Acta, 48, 823-35.CrossRefGoogle Scholar
Liu, F., and Chen, D. (1981) Fen Hsi Hua Hsueh, 9, 374-5 (in Chinese). Anal. Abstr. 42, 2B 130.Google Scholar
Magalhãtes, M. C. F., Pedrosa de Jesus, J. D., and Williams, P. A. (1986) Mineral Mag. 50, 33-9.Google Scholar
Neal, C., and Stanger, G. (1984) Ibid. 48, 237-41.Google Scholar
Nriagu, J. O. (1973) Geochim. Cosmochim. Acta 37, 367-77.CrossRefGoogle Scholar
Palache, C., Berman, H., and Frondel, C. (1951) Dana's System of Mineralogy, 7th ed., 2, John Wiley and Sons, New York.Google Scholar
Perrin, D. D., and Sayce, I. G. (1967) Talanta, 14, 833-42.CrossRefGoogle Scholar
Pinch, W. W., and Wilson, W. E. (1977) Mineral. Rec. 8, 17-37.Google Scholar
Robie, R. A., Hemingway, B. S., and Fisher, J. R. (1978) Thermodynamic Properties of Minerals and Related Substances at 298.15 K and 1 Bar (10-5 Pascal) Pressure and at Higher Temperatures. U.S. Geol. Surv. Bull. 1452.Google Scholar
Smith, R. M., and Martell, A. E. (1976) CriticalStability Constants, 4. Plenum Press, New York.CrossRefGoogle Scholar
Varian Techtron Pty. Ltd. (1979) Analytical Methods for Flame Spectroscopy. Varian Techtron, Springvale (Australia).Google Scholar