gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1992.056.383.08 Mineralogy The Stabilities of Secondary Tin Minerals: Abhurite and its Relationships to Sn(II) and Sn(IV) Oxides and Oxyhydroxides Edwards R. Gillard R. D. Williams P. A. * School of Chemistry and Applied Chemistry, University of Wales College of Cardiff, P.O. Box 912, Cardiff CF1 3TB, U.K.

Present address: Department of Chemistry, University of Western Sydney Nepean, P.O. Box 10, Kingswood, NSW 2747, Australia.

 6 1992 56 383 221 226 20 6 1991 16 9 1991 Copyright © 1992, The Mineralogical Society 1992 Abstract

The true formula of abhurite is Sn21Cl16(OH)14O6. A stability constant for the phase has been determined at 298.2 K. For the reaction Sn21Cl16(OH)14O6 (s) + 26H+ (aq) ⇌ 21Sn2+ (aq) + 16Cl− (aq) + 20H2O (1), log KH+ (298.2 K) is equal to −39.9 (7). This value is used to assess the relative stability of abhurite in the natural environment and to evaluate its modes of occurrence in relation to other secondary Sn(II) and Sn(IV) species.

 Keywords abhurite tin minerals stability constant