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Elucidating the crystal-chemistry of Jbel Rhassoul stevensite (Morocco) by advanced analytical techniques

Rhouta, Benaïssa and Kaddami, H. and Elbarqy, J. and Amjoud, M'barek and Daoudi, Lahcen and Maury, Francis and Senocq, François and Maazouz, Abderrahim and Gerard, Jean-François Elucidating the crystal-chemistry of Jbel Rhassoul stevensite (Morocco) by advanced analytical techniques. (2008) Clay Minerals, vol. 43 (n° 3). pp. 393-404. ISSN 1471-8030

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Official URL: http://dx.doi.org/10.1180/claymin.2008.043.3.05

Abstract

The composition of Rhassoul clay is controversial regarding the nature of the puremineral clay fraction which is claimed to be stevensite rather than saponite. In this study, the raw and mineral fractions were characterized using various techniques including Fourier transform infrared spectroscopy and magic angle spinning nuclear magnetic resonance (MAS NMR). The isolated fine clay mineral fraction contained a larger amount of Al (>1 wt.%) than that reported for other stevensite occurrences. The 27Al MAS NMR technique confirmed that the mineral is stevensite in which the Al is equally split between the tetrahedral and octahedral coordination sites. The 29Si NMR spectrum showed a single unresolved resonance indicating little or no short-range ordering of silicon. The chemical composition of the stevensite from Jbel Rhassoul was determined to be ((Na0.25K0.20) (Mg5.04Al0.37Fe0.20&0.21)5.61(Si7.76Al0.24)8O20(OH)4). This formula differs from previous compositions described from this locality and shows it to be an Al-bearing lacustrine clay mineral.

Item Type:Article
Additional Information:Thanks to The Mineralogical Society editor. The definitive version is available at http://www.minersoc.org/ The original PDF of the article can be found at Clay Minerals website : http://www.ingentaconnect.com/content/minsoc/cm/2008/00000043/00000003/art00005?token=004c15731db0e39412f415d7676255f706e2b6c2a6c386f2530482972715a614f6d4e227ab99
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > Institut National des Sciences Appliquées de Lyon - INSA (FRANCE)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Other partners > University of Cadi Ayyad - UCAM (MOROCCO)
Laboratory name:
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Deposited By: Nihad Lahdifi
Deposited On:21 Feb 2011 18:09

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