释义 |
> as lemmasPurbeck clay Clay consists mainly of aluminium silicate, and is derived mostly from the decomposition of feldspathic rocks. The various beds are distinguished geologically as boulder clay, Kimmeridge clay, London clay, Oxford clay, Purbeck clay, etc. Particular kinds of clay are known as brick clay, fatty clay, plastic clay, porcelain clay, and potter's clay; pipe-clay, etc. Cf. fireclay n.< |