Crystal chemical analysis of natural clay material of different genesis

Crystal chemical analysis of natural clay material that formed under different physicochemical parameters shows that the analyzed samples are represented in series I by almost pure smectite (K,Na,Mg,Ca) _x ·nH₂O·(Fe,Mg)₂(Si,Al,Fe)₄O₁₀(OH)₂, in series II by smectite with a small impurity (~15%) of quartz (SiO₂) and plagioclase (NaAlSi₃O₈/CaAl₂Si₂O₈). The studies are performed by X-ray diffraction, IR spectroscopy, electron microscopy, and microprobe analysis. It is shown that the values of d001 basal reflections of the smectites in question within 11–13 Å are due to the degree of cation occupation and hydration of the interlayer space, and differences in the frequencies of IR spectra are caused by isomorphic substitutions in the structure. Microprobe analysis results, calculated crystal chemical formulas, and values of b parameters are held only for the extreme terms in a series of dioctahedral ferric smectites: nontronites. The results reveal differences both in the composition, structure, properties, morphology and IR spectroscopic characteristics of nontronites of different origin.