Mineralogy and chemical composition of some laterites of Sri Lanka

Laterite samples have been collected from different parts of Sri Lanka and analysed mineralogically and chemically. The samples studied were collected from layers within individual vertical sections. Mineralogical analyses were made using XRD, DTA, DTG and TG methods whereas chemical analyses were made with wet chemical techniques. The laterites studied overlie several rock types differing in chemical composition. The analyses show that gibbsite is the most significant free aluminium mineral, whereas geothite and hematite are the main iron minerals. Even though bauxite composition is approached in some samples, the existence of sufficient commercial grade bauxite is still to be established.