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On the chemical composition of sepiolite and palygorskite

E. Garcia-Romero and M. Suarez
On the chemical composition of sepiolite and palygorskite
Clays and Clay Minerals (February 2010) 58 (1): 1-20


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 Mg-palygorskite 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.

ISSN: 0009-8604
EISSN: 1552-8367
Serial Title: Clays and Clay Minerals
Serial Volume: 58
Serial Issue: 1
Title: On the chemical composition of sepiolite and palygorskite
Affiliation: Universidad Complutense, Departamento de Cristalografia y Mineralogia, Facultad de Ciencias Geologicas, Madrid, Spain
Pages: 1-20
Published: 201002
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 62
Accession Number: 2010-039478
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 10 tables
Secondary Affiliation: Universidad de Salamanca, ESP, Spain
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, Copyright, Clay Minerals Society. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201022
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