On the chemical composition of sepiolite and palygorskite
García-Romero, E. (Universidad Complutense de Madrid. Departamento de Cristalografía y Mineralogía)
Suárez, M. (Universidad de Salamanca. Departamento de Geología)

Date:	2010
Abstract:	Many studies of the chemical composition of sepiolite and palygorskite have been carried out using analytical electron microscopy (AEM). According to the literature, a compositional gap exists between sepiolites and palygorskites, but the results presented here show that they may all be intermediate compositions between two extremes. The results of >1000 AEM analyses and structural formulae have been obtained for the samples studied (22 samples of sepiolite and 21 samples of palygorskite) and indicate that no compositional gap exists between sepiolite and palygorskite. Sepiolite occupies the most magnesic and trioctahedral extreme and palygorskite the most aluminic-magnesic and dioctahedral extreme. Sepiolite and palygorskite with intermediate compositions exist between the two pure extremes: (1) sepiolite with a small proportion of octahedral substitution; (2) palygorskite with a very wide range of substitution (the pure dioctahedral extreme is unusual); and (3) intermediate forms, Al-sepiolite and Mgpalygorskite with similar or the same chemical composition. The chemical compositions of the intermediate forms can be so similar that a certain degree of polymorphism exists between Al-sepiolite and Mg-palygorskite.
Note:	Altres ajuts: CICYT/CGL2006-09843
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Chemical composition ; Octahedral sheet ; Octahedra cations ; Palygorskite ; Sepiolite
Published in:	Clays and Clay Minerals, Vol. 58, Núm. 1 (2010) , p. 1-20, ISSN 1552-8367

DOI: 10.1346/CCMN.2010.0580101

20 p, 681.5 KB  UAB restricted access

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