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Identification of vermiculite by transmission electron microscopy and X-ray diffraction

Published online by Cambridge University Press:  09 July 2018

H. Vali
Affiliation:
Department of Geological Sciences, McGill University, 3450 University Street, Montreal, Quebec, Canada H3A 2A7
R. Hesse
Affiliation:
Department of Geological Sciences, McGill University, 3450 University Street, Montreal, Quebec, Canada H3A 2A7

Abstract

The expandability of K-depleted biotite and natural vermiculite was studied using transmission electron microscopy (TEM) and X-ray diffraction (XRD). K-depletion in layer-silicates was achieved by treating ultrathin sections with 0·1 m CaCl2 and BaCl2 solutions. The natural sample of biotite, which by XRD revealed no expandability on ethylene glycol or glycerol solvation, displayed 10–15% expanded layers when viewed by TEM after alkylammonium intercalation. The proportion of expanded layers increased after CaCl2 treatment. XRD of vermiculite samples revealed two sets of expandable interlayers after alkylammonium treatment, corresponding to two types of particles with different layer structures observed by TEM. Identification of vermiculite by TEM based on basal spacings is reliable with alkylammonium treatment. Intercalation of alkylammonium ions into the interlayers of vermiculite improved the degree of stacking order of the 2:1 layers.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1992

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