A comparative X-ray diffraction, Mössbauer and NMR spectroscopic study of the vermiculites from Bébu Bousera, Morocco and Palabora, Republic of South Africa
Authors: Badreddine, R.; Vandromael, D.; Fransolet, A.-M.; Long, G. J.; Stone, W. E. E.; Grandjean, F.
Source: Clay Minerals, Volume 37, Number 2, 1 June 2002 , pp. 367-376(10)
Publisher: Mineralogical Society
Abstract:Five vermiculite samples collected from Béni Bousera, Morocco and four from Palabora, South Africa were investigated by X-ray diffraction, chemical analysis, 57Fe Mössbauer spectroscopy, and 27Al magic angle spinning nuclear magnetic resonance. The X-ray diffraction studies indicate that all vermiculites have very similar crystallographic parameters. The chemical analyses and the NMR spectra indicate that the Béni Bousera vermiculites contain Al3+ cations in both octahedral and tetrahedral sheets and the Palabora vermiculites contain Al3+ in the tetrahedral sheet. The Mössbauer spectra indicate that the Béni Bousera vermiculites contain more Fe2+ cations than the Palabora vermiculites and do not contain tetrahedral Fe3+ cations. The different cation compositions and distribution in the two sets of vermiculites may result from different parent minerals, i.e. chlorite in the case of Béni Bousera and phlogopite in the case of Palabora, and different genetic processes, i.e.weathering in Béni Bousera and hydrothermal alteration in Palabora.
Document Type: Research Article
Publication date: 2002-06-01