Mineralogy of the Swat kaolin deposits, Pakistan

This study provides the mineralogical and compositional characterization of the Swat kaolin deposits of Pakistan and their parent and enclosing rocks. The mineral assemblage of the raw kaolin of these primary deposits, has been determined to include disordered kaolinite, paragonite, clinochlore, epidote, disordered calcian albite, quartz, calcite, montmorillonite, and halloysite. Amongst the five size-fractions prepared in this study (raw, < 63gm, < 10 mu m, < 5 mu m, and < 2 mu m), the kaolin group mineral content increases in the finer fractions. The deposits are derived from feldspar-rich primary rock types that are mainly calc-alkaline quartz diorites, tonalites, granitoids, and pegmatites. Plagioclase chemistry exhibits negative correlations of SiO2 versus Al2O3, and CaO versus Na2O, due to either or both of fractional crystallization, and hydrothermal replacement. The mineralogical attributes that influence the industrial usage of Swat kaolin are highlighted.