The Buwambo kaolin deposit in central Uganda: Mineralogical and chemical composition

Kaolin from the Buwambo deposit, located about 27 km north of Kampala (Uganda), has been analyzed for its mineralogical and chemical composition. The kaolin is derived from granite of the basement, which is exposed due to deeply weathered Buganda-Toro cover rocks. Kaolinite is the dominant mineral, with quartz and muscovite/illite as accessory minerals. Chemical data show that the kaolin is composed mainly of SiO2 and Al2O3, with the other oxides being present in trace amounts. The depletion in Ti, Fe, Mn, Mg, Ca, Na, and K not only shows the extent of the kaolinization, but also gives Buwambo kaolin its almost white color. The kaolinization and weathering processes have enriched Ni and depleted other trace element contents in the Buwambo kaolin. The chondrite-normalized rare earth element (REE) patterns show enrichment in the light REEs, with a negative Ce anomaly. The REE pattern and the content of the other trace elements, show evidence of alteration and weathering processes related to kaolinization. The mineralogical and chemical compositions indicate that the kaolin is suitable for industrial use.