Provenance of the Kgwakgwe kaolin deposit in Southeastern Botswana and its possible utilization

Petrographic, mineralogical and geochemical studies were carried out on kaolin samples from the Kgwakgwe kaolin deposit in southeastern Botswana in order to understand sediment provenance and suggest its possible utilization. Kaolinite is dominant, whereas illite occurs in a stratigraphically localized area in the northwestern flank of the deposit. Accessory minerals are quartz, sericitic muscovite, goethite, halloysite and hematite. Cryptomelane, bixbyite, and pyrolusite manganese oxide (Mn oxide) associated with the kaolin. Hinckley crystallinity index and differential thermal analyses (DTA) values for dehydroxylation and mullitization peak temperatures were obtained for Kgwakgwe kaolinite. Kaolinite in the deposit occurs as irregular platelets, well-developed irregular flakes and a few pseudo-hexagonal stacks. Sediment provenance and alteration, and kaolinite purity is explained using kaolin mineralogy, particle morphology, and major and trace element geochemical data. The data suggests that the kaolin is derived from the alteration of terrigenous sediments that may have weathered from either the granite of the Gaborone Granite Complex (GGC) or the rhyolite of the Kanye Volcanic Formation (KVF) and deposited in the Kgwakgwe basin. The source sediments form part of the late Archaean lower Transvaal Supergroup and could have been deposited in a shallow lagoonal/lacustrine environment. On the basis of the results obtained from granulometric and mineralogical analyses as well as chemical and diagnostic evaluative analyses, the deposit could be exploited in the fabrication of tiles, bricks, sanitary wares and ceramic ware. It could also be used in rubber and plastic industries as well as making of pesticides, insecticides, and crayons. The raw clay will have to be beneficiated in order to optimize grade and recovery.