China clay

Highley, D.E.

China clay

Highley, D.E.. 1984 China clay. London, UK, HMSO, 71pp. (Mineral Dossier No. 26)

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Abstract/Summary

China clay, or kaolin as it is internationally known, is a white clay consisting predominantly of kaolinite. The mineral forms the basis of a large extractive industry in the United Kingdom and the deposits of Southwest England are world famous for their high quality. The United Kingdom is, after the USA, the second largest producer of kaolin but the leading world exporter, with over 80 per cent of annual output exported. In 1982 the United Kingdom produced some 2.4 million tonnes of kaolin valued at about £135 million. The deposits are a major mineral resource and, until the advent of North Sea oil, kaolin was the United Kingdom's major mineral export. Although originally valued for use in whiteware ceramics, kaolin is now used mainly in papermaking (some 80 per cent of United Kingdom output), both for paper coating and paper filling. Subsidiary amounts are used as fillers in paint, rubber and plastics and have a wide range of other uses. The deposits of Southwest England were formed by the in situ alteration of the feldspar component (principally sodic plagioclase) of the Variscan granites, all of which have been worked. Production has, however, centred mainly on the St Austell Granite, which accounts for 75 per cent of production, and the southwestern margin of the Dartmoor Granite (20 per cent). Small quantities are produced on Bodmin Moor and near Land's End. The kaolinised granite-the clay matrix-consisting principally of quartz, micaceous mineral, feldspar and kaolinite, is hydraulically mined. Kaolinite, occurring mainly in the <20 μm fraction, is recovered principally by wet classification by sedimentation, hydrocycloning and centrifuging. Total clay yields are usually in the range 10 to 15 per cent and thus large quantities of waste are produced, which has a major impact on the environment. Marketable grades are assessed for brightness, particle size distribution, viscosity and, in the case of potting clays, a wide, range of ceramic properties.

Item Type:

Publication - Report

Programmes:

BGS Programmes > Economic Minerals

Funders/Sponsors:

British Geological Survey

Additional Keywords:

Mineral, China clay

NORA Subject Terms:

Earth Sciences

Date made live:

12 Aug 2025 09:42 +0 (UTC)