Smectite interstratification

It is evident that, in addition to smectitic interstratifications (the effect of which on illite crystallinity have been frequently el iminated by glycolation and/or deconvolution of the basal reflections), the various contents of interlayer K may considerably affect illite crystallinity. Recent issues prove that mo st probably, the amount of K should increase with increasing grade (temperature) (Hunziker et al. 1986 Livi et al. 1997). 

Srodon, J. (1980) Precise identification of illite/smectites interstratifications by x-ray powder diffraction. Clay Clay Miner., 28, 401-411. 

A mixture of intercalating clays is generally found in the subsurface. Interstratification of kaolinite and smectite has been reported in some cases (e.g., Schultz et al. 1971 Lee et al. 1975a, 1975b Yerima et al. 1985). This fact is reflected in an XRD... 

In reality, soil clays are often not so well defined. Interstratification is common, with, for example, intergrades of vermiculite and illite or smectite and illite being found. This means that some layers in the clay... 

The I/S peak at 11.8 A in the pattern of soil developed on the Del Rio Clay indicates ordered interstratification as opposed to the random interstratification in the BS I/S (16.9 A peak). Soils developed on the Buda Limestone contain smectite and yield XRD patterns similar to Edwards soil A. Therefore, neither the Del Rio Clay nor the Buda Limestone is the source of the Barton Springs suspended sediment. 

The similar structure of illite and smectite allows mixing or interstratification of 2 1 units to form mixed-layer clays. Most illites and smectites are interstrati-fied to a small degree, but they are not classified as such until detectable by X-ray diffraction. As one might expect, illite-smectite mixed-layer clays have intermediate cation exchange capacity between the end-member compositions. 

Figure 1.11. Some effects of pedochemical weathering on phyllosilicate surfaces. Weathering produces interlayer hydroxy-polymers, interstratification, and external-surface organic and inorganic polymer coatings on smectite. On kaolinite, organic and iron oxide coatings are produced by weathering. After Jenne ...

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