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Oxidized tourmalines; a combined chemical, XRD and Moessbauer study

Adam Pieczka and Janusz Kraczka
Oxidized tourmalines; a combined chemical, XRD and Moessbauer study
European Journal of Mineralogy (April 2004) 16 (2): 309-321

Abstract

Thermal oxidation of Fe (super 2+) in tourmalines of the schorl-dravite series was induced by the gradual annealing of powdered samples in air at > 600 degrees C. The a unit cell parameter decreases while c slightly increases as a result of thermal modification of the X, Y, Z, B and T polyhedra sizes, particularly those primarily occupied by Fe (super 2+ ) or traces of Mn (super 2+) . The Y octahedron shrinks proportionally to the original Fe (super 2+) content, while the Z octahedron shows a small expansion. In Moessbauer spectra of oxidized tourmalines the Fe (super 2.5+) mixed valence doublet and the Fe (super 3+) doublets progressively increase with advancing oxidation. These changes are explained in terms of progressive generation of Fe (super 3+) in place of primary Fe (super 2+) within the triad of the Y sites. Annealing of tourmalines after complete oxidation increases Fe (super 3+) -Al disordering among the Y and Z sites up to the decomposition of the structure at around 900 degrees C.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 16
Serial Issue: 2
Title: Oxidized tourmalines; a combined chemical, XRD and Moessbauer study
Affiliation: University of Mining and Metallurgy, Department of Mineralogy, Petrography and Geochemistry, Cracow, Poland
Pages: 309-321
Published: 200404
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 37
Accession Number: 2004-042033
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 5 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 200412
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