Interparticle diffraction; a new concept for interstratification of clay minerals

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Authors:Nadeau, P. H.; Wilson, M. J.; McHardy, W. J.; Tait, J. M.
Author Affiliations:Primary:
Macaulay Inst. Soil Res., Dep. Miner. Soils, Aberdeen, United Kingdom
Volume Title:Clay Minerals
Source:Clay Minerals, 19(5), p.757-769. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0009-8558
Publication Date:1984
Note:In English. 27 refs.; illus. incl. 2 tables
Summary:A new conceptual model for interstratified clays is proposed, based on complementary use of TEM and XRD. Clays yielding interstratified XRD patterns are composed of aggregates of fundamental particles whose interfaces are capable of adsorbing water and organic molecules; the interstratified XRD character results from an interparticle diffraction phenomenon. Smectites are primarily composed of particles 10 A thick corresponding with elementary 2:1 silicate layers. Nearest-neighbour regularly interstratified illite-smectite (K-rectorite) is composed of particles of elementary 'illite' 20 A thick, corresponding with two silicate layers coordinated by a single plane of K ions. Regularly interstratified chlorite-smectite (corrensite) consists of particles 24 A thick corresponding with two silicate layers coordinated by a single brucitic sheet. The layer sequence examined by XRD is determined by the types and proportions of particles present within the clay material. Thus a sedimented aggregate of 20 A elementary 'illite' particles appears to be a regularly alternating sequence of illite and smectite layers by XRD. Randomly interstratified illite-smectite and chlorite-smectite can be synthesized by making suspensions of the < 0.1 mu m fractions of smectite with those of K-rectorite and corrensite respectively, providing experimental confirmation of the proposed model. Unusual associations, such as three-component illite-chlorite-smectite interstratified systems can be synthesized by making mixed-suspensions of K-rectorite and corrensite. Long-range regularly interstratified illite-smectite of the IIS and IIIS types are composed primarily of fundamental 'illite' particles 20-50 A thick. Conventional illite is composed primarily of particles >50 A thick. [D.J.M.]
Subjects:Adsorption; Chlorite; Chlorite group; Clay mineralogy; Clay minerals; Corrensite; Crystal structure; Illite; Mineral data; Minerals; Mixed-layer minerals; Models; Organic compounds; Rectorite; Saponite; Sheet silicates; Silicates; Smectite; TEM data; X-ray data; Organic materials
Abstract Numbers:85M/1298
Record ID:1985053186
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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