An ⁵⁷Fe Mössbauer Spectral Study of Vermiculitization in the Palabora Complex, Republic of South Africa

Abstract

Two phlogopite, two mixed-layer, phlogopite-vermiculite, and two vermiculite samples collected from the Palabora Complex of South Africa have been investigated at 295 K by X-ray diffraction, chemical analysis, and Mossbauer spectroscopy. In addition the temperature dependence of the Mossbauer spectra has been measured between 95 and 295 K for one phlogopite and one mixed-layer sample. The results of the chemical analyses and the Mossbauer spectra improve our knowledge of the vermiculitization process in the Palabora Complex. Both techniques indicate oxidation of the Fe ions during the sequence: Phlogopite → mixed-layer → vermiculite. Further, the Mossbauer spectra indicate that Fe oxidation occurs mainly in the octahedral sites and suggest that migration and oxidation of the Fe2+ ions from the octahedral sites to the tetrahedral sites may occur during the transformation of phlogopite into a mixed-layer phase. Finally, the vermiculitization process involves both Fe oxidation and loss of K with a concomitant increase in the Mg content.

Department(s)

Chemistry

Keywords and Phrases

Clay Mineral; Iron; Mössbauer Spectroscopy; Vermiculite; X-ray Diffraction; South Africa; Composition Effects; Iron; Mössbauer Spectroscopy; Oxidation; Phase Transitions; Thermal Effects; X Ray Diffraction Analysis; Phlogopite; Vermiculite; Vermiculitization; Clay Minerals; Chemical Analyses

International Standard Serial Number (ISSN)

0009-8558

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2000 Mineralogical Society, All rights reserved.

Publication Date

01 Sep 2000

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