Identification of illite/montmorillonite interstratifications by X-ray powder diffraction

Illite/montmorillonite interstratifications are expressed in terms of Reichweite (S) and the ratio of illite-layer to montmorillonite-layer. The graph for identification of illite/montmorillonite interstratification is proposed in this paper. The values of Reichweite (S) and the ratio of illite-layer to montmorillonite-layer can be read from the graph, if only the two values (Δ2θ1 and Δ2θ2) of the angular differences between three 00l reflections of interstratified illite/montmorillonite treated with ethylene glycol are plotted on the graph, and an application to natural samples is shown.