Near-infrared reflectance spectra of mixtures of kaolin-group minerals; use in clay mineral studies

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Authors:Crowley, James K.; Vergo, Norma
Author Affiliations:Primary:
U. S. Geol. Surv., Reston, VA, United States
Volume Title:Clays and Clay Minerals
Source:Clays and Clay Minerals, 36(4), p.310-316. Publisher: Clay Minerals Society, Clarkson, NY, United States. ISSN: 0009-8604
Publication Date:1988
Note:In English. 14 refs.; illus. incl. 2 tables
Summary:Near-infrared (NIR) reflectance spectra for mixtures of ordered kaolinite and ordered dickite have been found to simulate the spectral response of disordered kaolinite. The amount of octahedral vacancy disorder in nine disordered kaolinite samples was estimated by comparing the sample spectra to the spectra of reference mixtures. The resulting estimates are consistent with previously published estimates of vacancy disorder for similar kaolin minerals that were modeled from calculated X-ray diffraction patterns. The ordered kaolinite and dickite samples used in the reference mixtures were carefully selected to avoid undesirable particle size effects that could bias the spectral results. NIR spectra were also recorded for laboratory mixtures of ordered kaolinite and halloysite to assess whether the spectra could be potentially useful for determining mineral proportions in natural physical mixtures of these two clays. Although the kaolinite-halloysite proportions could only be roughly estimated from the mixture spectra, the halloysite component was evident even when halloysite was present in only minor amounts. A similar approach using NIR spectra for laboratory mixtures may have applications in other studies of natural clay mixtures. [R.E.S.]
Subjects:Chemical properties; Clay mineralogy; Clay minerals; Dickite; Experimental studies; Infrared spectroscopy; Kaolinite; Mineralogy; Minerals; Sheet silicates; Silicates; Spectroscopy; X-ray analysis
Abstract Numbers:89M/1547
Record ID:1988072654
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland
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