Mineral Constituents and Kaolinite Crystallinity of the <2 μm Fraction of Cretaceous-Paleogene/Neogene Kaolins from Eastern Dahomey and Niger Delta Basins, Nigeria

Abstract This study examines the mineral composition and kaolinite crystallinity of Cretaceous and Paleogene/Neogene kaolins from Nigeria based on X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy data of the <2 μm fraction. The purpose of this was to assess the minerals present, structural order, and possible industrial applications of the kaolins. A total of twenty-eight (28) samples comprising of fifteen (15) Cretaceous and thirteen (13) Paleogene/Neogene kaolins were analysed. The XRD results showed that both the Cretaceous and Paleogene/Neogene kaolins have kaolinite as the dominant phase followed by quartz with anatase, hematite, and goethite occurring in minor quantities. Based on the mineralogical composition, the Paleogene/Neogene deposits were classified as sandy kaolin and the Cretaceous deposits were classified as pure kaolin. The kaolinite structural order for the Cretaceous pure kaolin was higher than that obtained for the Paleogene/Neogene sandy kaolin with more quartz, iron, and titanium oxides. The economic consideration of the deposits showed that the sandy kaolin type can be used in pigment industrial applications whereas the pure kaolin type can be used in refractory, fiberglass, and ceramic industrial applications.