%0 Journal Article
%A García Romero, Emilia
%A Súarez Barrios, Mercedes
%T On the chemical composition of sepiolite and palygorskite
%D 2010
%@ 0009-8604
%U https://hdl.handle.net/20.500.14352/41987
%X Many studies of the chemical composition of sepiolite and palygorskite have been carried outusing analytical electron microscopy (AEM). According to the literature, a compositional gap existsbetween sepiolites and palygorskites, but the results presented here show that they may all be intermediatecompositions between two extremes. The results of >1000 AEM analyses and structural formulae havebeen obtained for the samples studied (22 samples of sepiolite and 21 samples of palygorskite) and indicatethat no compositional gap exists between sepiolite and palygorskite. Sepiolite occupies the most magnesicand 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 ofsubstitution (the pure dioctahedral extreme is unusual); and (3) intermediate forms, Al-sepiolite and Mgpalygorskitewith similar or the same chemical composition. The chemical compositions of theintermediate forms can be so similar that a certain degree of polymorphism exists between Al-sepiolite andMg-palygorskite.
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