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chalk (see Limestone)
china clay
China clay or kaolin is a commercial clay composed principally of the hydrated aluminosilicate clay mineral kaolinite. The commercial
value of china clay is based on the mineral’s natural whiteness and its fine, but controllable, particle size. Particle size
affects fluidity, strength, plasticity, colour, abrasiveness and ease of dispersion. Other important properties include its flat particle
shape, which increases opacity or hiding power, its soft and non-abrasive texture, due to the absence of coarser impurities, and
its chemical inertness. These key properties distinguish china clay from the other kaolinitic clays produced in Britain, such as ball
clay and fireclay. The kaolinite content of processed kaolin varies, but is generally in the range 75 per cent to 94 per cent. China
clay is mainly used in papermaking as a coating pigment and filler, although the ceramics industry, and its use as a filler in paint,
rubber and plastics are also important markets.
China clay resources in Britain are confined to the granites of south-west England. The deposits are world famous for their size
and quality and have provided over 165 million tonnes of china clay since production records began in the late 19th century. All
the main granite intrusions have been worked to a limited extent in the past. Today production is confined to the St Austell Granite
and the south-western margin of the Dartmoor Granite, and on the adjacent but separate Crownhill Down Granite. Production
from the Bodmin Moor Granite ceased in 2001 with the closure of the Stannon Pit. The St Austell Granite is by far the most important
source accounting for about 85 per cent of total sales. The industry is of considerable national and regional importance.
China clay sales have been on a declining trend since peak output of 3.28 million dry tonnes in 1988. Sales declined from
1 945 000 dry tonnes in 2004 to an estimated 1 800 000 dry tonnes in 2005. In 2004 88 per cent of UK china clay production
was exported, mainly to Europe.
The extraction and processing of china clay involves the production of very large quantities of waste. China clay waste is exempt
from the Aggregates Levy and sales for aggregate use have increased from 2.1 million tonnes in 2001 to 2.5 million tonnes in
2004. Sales are mainly in the south-west, although small quantities are also shipped to London and the south-east. However,
shipments of china clay aggregate from the Port of Par declined from 160 000 tonnes in 2003 to 62 000 tonnes in 2004. This is
due to the rising cost of sea freight, the cost of fuel and the lack of available vessels. Plans for a significant expansion in shipments
are unlikely to materialise in the short term.
Imerys Minerals Ltd is the largest china clay producer accounting for about 85 per cent of total output with operations based on
the St Austell Granite in Cornwall and the south-western margin of the Dartmoor Granite in Devon. The company is a subsidiary
of the Imerys Group of France, which is the world’s leading kaolin producer. Goonvean Ltd, a privately-owned company, operates
five quarries in the St Austell Granite and WBB Minerals operates two sites on the Dartmoor Granite and Crownhill Down
Granite.
united Kingdom summary 2000–2004
Commodity 2000 2001 2002 2003 2004 2000 2001 2002 2003 2004
30
Tonnes £ thousand
china clay
Production (sales) (a) (b) 2 376 057 2 204 156 2 162 815 2 097 137 1 944 955
Imports 42 537 95 337 56 416 72 719 108 260 6 275 8 140 5 433 8 473 9 439
Exports (a) (b) 2 074 548 1 928 230 1 899 220 1 862 437 1 728 161
(a) Dry weight. (b) Source: The Kaolin and Ball Clay Association.
china stone
united Kingdom summary 2000–2004 Tonnes
Commodity 2000 2001 2002 2003 2004
china stone–see Feldspar
Production 3 645 2 995 1 896 2 865 1 835