Characterisation of kaolinitic clays from the Ivory Coast (West Africa)

Clays from different deposits in the Ivory Coast (Adattié (ADA), Nieki (NIE), Grand-Bassam (BAS), Nigui-Saff (NS)) were studied using various techniques. Their chemical compositions were determined by X-ray fluorescence and the most important crystalline phases were identified by X-ray diffraction. Kaolinite is the dominant mineral phase with minor amounts of other minerals including quartz, haematite, goethite, lepidocrocite and illite. The oxidation state and coordination of iron, essentially present as Fe(III), were investigated using 57Fe Mössbauer spectroscopy before or after extraction of iron oxides with dithionite–citrate–bicarbonate (DCB). Samples from Grand-Bassam contain important amounts of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). Some samples from Nigui-Saff contained large amounts of haematite. These clays could be used in the ceramics industry and possibly in environmental protection to immobilise pollutants.