2017 Volume 21 Issue 2 Pages 29-34
High quality kaolin is mined at Meetiyagoda in southwestern Sri Lanka. The deposit occurs in a swampy area within the low-lying coastal region having a tropical wet climate. The kaolin clay beds form part of the Cenozoic fluvial sediments overlying the granulite and pegmatite of the Highland Complex formed by the late Neoproterozoic-Cambrian orogeny. The sedimentary clays are composed mainly of kaolinite and quartz. X-ray powder diffraction and scanning electron microscopy have revealed that kaolinite is well-crystallized variety and the platy crystals are not broken in the sedimentary clay. The sedimentary kaolin is considered to have been formed by intense tropical weathering of the aluminous granulite and pegmatite, and subsequently transported and deposited into low-lying swamps or marshes near the weathering crust over the basement rock. The kaolinite crystals might have undergone partial recrystallization in the swampy environment.
