Evaluating the quantification of the clay mineralogy of the Rupelian Boom Clay in Belgium by a detailed study of size fractions

The quantification of the whole rock mineralogical composition of clay-rich sediments can be achieved by quantifying the detailed clay mineralogy in a fraction which concentrates most of the clay minerals (often the fraction <2 μm) and integrating this information with a mineralogical composition derived from modeling a randomly oriented powder diffraction pattern of the bulk sample. Although this approach is effective, as evidenced by its performance in the Reynolds Cup, the representativeness of the isolated fraction for the entire clay mineral population is not indisputable, as clay minerals are known to occur in coarser fractions as well. Therefore, this study investigates the representativeness of the fraction <2 μm by isolating and quantifying the mineral composition of all size fractions of the Rupelian Boom Clay (Belgium). In addition, the study of size fractions is used to quantify and correctly integrate muscovite into a whole rock mineral composition.