Bulletin of the Geological Society of Malaysia, Volume 20, August 1986, pp. 601 – 617
Geological Survey of Malaysia, P.O. Box 1015, lpoh, Perak.
Abstract: The kaolin deposits of more than 50 million tonnes and distributed over 70 sq km occur in the Bidor area, Peninsular Malaysia. They are believed to have been formed hydrothermally. The area is underlain by Paleozoic metasediments which are intruded by the Changkat Rembian granite of Late Triassic age. Argillization is pervasive, affecting both the metasediments and the southern half of the Changkat Rembian granite which is intensely sheared.
The residual kaolin deposits derived from the alteration of granitic and metasedimentary rocks may be distinguished by their field, physical, chemical and mineralogical characteristics. Kaolin of granitic parent rock is generally characterized by relict granitic texture, high grit and lower clay content compared to metasedimentary kaolin. The granitoid kaolin generally has a higher brightness. Quartz, in vein and granular forms, is the most predominant non-clay mineral common to both types of deposits. In the clay mineral fraction, the assemblage consists mainly of kaolinite and trace to small amounts of illite, montmorillonite/vermiculite, quartz and feldspar. However, in places, illite predominates over kaolinite in some residual metasediments to form illite deposits.
It was mining of placer tin which led to the exposure of most of the kaolin deposits. Quartz veins/stringers carrying tourmaline and cassiterite with occasional wolframite and gold have been found in the Changkat Rembian granite and along its contact with the metasediments. Though the genetic relationship between gold, tin and tungsten mineralization and argillization is uncertain, temporally argillization is the youngest.
The Malaysian kaolin industry originated in the 1930s from this area. Currently, there are about a dozen processing plants which produce more than two-thirds of Malaysia‘s kaolin output of about 50,000 tonnes per annum. Both wet and dry processes are used to produce various grades of kaolin for ceramic, paper, paint, plastics and rubber industries. The most refined kaolin produced is of paper-filler grade.