A dispersion-centrifugation-decantation procedure was used to isolate various particle size fractions from a sample of clay (<2 μm fraction) separated by sedimentation from the Ap horizon of a Webster soil (fine-loamy, mixed, mesic Typic Haplaquoll). The 0.02-0.06 μm size fraction was found to be enriched in an illitic phase associated with randomly interstratified smectite/illite. X-ray powder diffraction, chemical analysis, and high-resolution transmission electron microscopy confirmed that most of the illitic material in the 0.02-0.06 μm size fraction was composed of two-layer elementary illite particles with a layer charge of -0.47 per formula unit. The results demonstrate that this low-charge illitic phase can be physically separated from soil materials and that the low-charge illitic phase has chemical, morphological, and mineralogical properties that are uniquely different from those of smectite and illite.
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- Chemical analysis
- Elementary particle
- High-resolution transmission electron microscopy