Published online by Cambridge University Press: 01 January 2024
Recent development of the intersalation method by which kaolinite (as well as dickite and halloysite) is expanded makes possible the application of X-ray diffraction to qualitative and semiquantitative determinations of these mineral species. It also permits their distinction from the X-ray-thermally similar intergradient 2:1–2:2 layer silicates which are not affected by the treatment. Intergradient 2:1–2:2 layer silicates are developed by interlayer precipitation of hydroxides of aluminum, iron, and magnesium during pedogeochemical weathering and probably also during burial in sediments. The quantitative determination of kaolinite-halloysite by NaOH differential dissolution is completely corroborated by the qualitative, semiquantitative X-ray diffraction intersalation technique with respect to their clear differentiation from chlorite and intergradient clays.