Kaolin is named after the Chinese locality “Kauling” or “Kao-ling” meaning high ridge. It is the name of a hill near Yaochao Fu, mainland China, where clay was mined centuries ago. Kaolin is a soft, white plastic clay consisting of a loose aggregation of randomly oriented stacks of kaolinite flakes.

Kaolin deposits are classified as either primary or secondary. Primary kaolins results from residual weathering or hydrothermal alteration ( or kaolinisation ) or alkali feldspar-rich rocks such as granite or gneiss, whilst secondary kaolins are of sedimetary origin. The mineralogical and chemical composition of kaolin depends on the nature of the parent rock and the type and degree of alteration. Both primary and secondary kaolins occur in South Africa.

For commercial production, certain characteristics may be altered through processing and / or blending – kaolin may be processed dry for use in paint, ceramics, rubber, or wet ( water washing ) for use as filter in paper, paint or plastics. Futher value-addition may include high-intensity magnetic seperation, ozonisation, delamination, micronising, nanosizing, calcining, pelletising and UV-sterilizing. Local kaolin is used as a filter in paint, plastics and rubber, as a carrier in cosmetics and pharmaceuticals, animal feeds, fertilizers and pesticides and as a main constituent in ceramics, specific refractories and heavy clay products.

In 2004. there were 7 koalin producers in South Africa ( with production from 10 pits ) located in the Cape Peninsula ( Western Cape ), Grahamstown district ( Eastern Cape ), and along the eastern Gauteng border ( Pretoria / Bronkhorstspruit area ). Both the B13 ball clays and the Gauteng plastic clays are often marketed and sold as kaolin. Reserves of all kaolin grades are in excess of 35 Mt. These reserves are estimated to be sufficient for more than 100 years at current production rates. Several medium / high- grade deposits have since been discovered and / or prospected, although orebody continuity and quality have not been accurately measured. Other important constraints include location and level of extraction / processing costs.

South Africa production is relatively small ( 0.4% of global production ), compared to that of major producers. Globally, kaolin ranks among the top seven industrial minerals. The world leaders in kaolin are also the countries with the largest reserves: China, Brazil, USA and UK.