The ball clay and china clay industries of Southwest England in 2000

The ball clay and china clay deposits of Southwest England are kaolinitic clays, but have very different origins. Ball clay is a sedimentary clay which originated from Palaeogene chemical weathering mantles developed on a variety of older rocks, which were eroded and transported into structural basins, together with sands and lignites. It is mainly valued for its strength and plasticity, combined with a white or near-white fired colour, and is mainly used in ceramics. China clay has been produced in situ by the kaolinization of granite in a series of fluid/rock hydrothermal and supergene interactions. It is mainly used as a white inert filling and coating material in paper. Other uses include ceramics, paint and plastics. Ball clay (1.07 Mt in 2000) and china clay (2.38 Mt in 2000) production are two of the largest industrial mineral activities in the UK, both in volume and value, after constructional raw materials. Over 80% of the production is exported, making kaolinitic clay from SW England the second most important mineral export from the UK after petroleum.