Mineralogical Variations among the Kaolin Deposits in Malaysia

Abstract

Abstract -Some kaolin deposits representing the primary and secondary deposits from Malaysia were analyzes for their mineralogical composition to examine the effect of source rock on the mineralogy of the primary kaolin deposits and to compare the nature and mineralogy of the secondary with the primary deposits. The clay minerals of the primary deposits from the Ipoh and Sarawak areas that formed by the weathering of granites and diorites respectively are dominated by kaolinite, while the primary deposit from the Bidor area that formed as a result of weathering of schist is composed of a mixture of kaolinite, muscovite, and smectite. Assuming that the primary deposits in these areas were formed under the same paleoclimatic conditions, the variations in the mineralogy of these deposits reflect mainly the compositions of primary source rocks. Predominance of kaolinite in the Ipoh and Sarawak deposits is due to the relative abundance of feldspar minerals (more Al) in the granite and diorite source rocks in these two areas. On the other hand, occurrence of smectite and muscovite in the primary kaolin deposits from Bidor area reflect the mineralogical composition of the parent rock in this area, which is mica-schist. Abundance of illite in the secondary kaolin deposits from the Mersing area suggests a marine depositional setting of these deposits where illlite formed due to the K uptake by clay minerals from the seawater. The less quartz (sand fraction) and more clay minerals (silt and clay fractions) in the secondary kaolin deposits are due to the relative enrichments of the fine fractions during the transportation of these deposits from the source to the depositional site.