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china clay,one of the purest of the clays, composed chiefly of the mineral kaolinitekaolinite
, clay mineral crystallizing in the monoclinic system and forming the chief constituent of china clay and kaolin. It is a hydrous aluminum silicate commonly formed by the weathering and decomposition of rocks containing aluminum silicate compounds; feldspar is a chief
..... Click the link for more information. usually formed when granite is changed by hydrothermal metamorphismmetamorphism,
in geology, process of change in the structure, texture, or composition of rocks caused by agents of heat, deforming pressure, shearing stress, hot, chemically active fluids, or a combination of these, acting while the rock being changed remains essentially in the
..... Click the link for more information. . Usage of the terms china clay and kaolin is not well defined; sometimes they are used synonymously for a group of similar clays, and sometimes kaolin refers to those obtained in the United States and china clay to those that are imported. Some authorities term as china clays the more plastic of the kaolins. China clays have long been used in the ceramic industry, especially in fine porcelains, because they can be easily molded, have a fine texture, and are white when fired. France's clays are made into the famous Sèvres (see A. BrongniartBrongniart, Alexandre
, 1770–1847, French geologist, mineralogist, and chemist. As director of the Sèvres porcelain factory from 1800, he was responsible for its international fame.
..... Click the link for more information. ) and Limoges potteries. These clays are also used as a filler in making paper. In the United States, deposits are found primarily in Georgia, North Carolina, and Pennsylvania; china clay is also mined in England (Cornwall) and France.
china clay[′chī·nə ‚klā]
A high-grade white kaolin composed principally of the mineral kaolinite, and often occurring as a lenticular-shaped body; used in the manufacture of ceramics, paper, rubber, catalysts, and ink.