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Clay is a type of fine-grained natural soil material containing clay minerals [1] (hydrous aluminium phyllosilicates, e.g. kaolinite, Al 2 Si 2 O 5 4). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide .
Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al 2 Si 2 O 5 4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay minerals form in the presence of water [1] and have been important to life, and many theories of abiogenesis ...
Clay tempered with sand, grit, crushed shell or crushed pottery were often used to make bonfire-fired ceramics because they provided an open-body texture that allowed water and volatile components of the clay to escape freely. The coarser particles in the clay also acted to restrain shrinkage during drying, and hence reduce the risk of cracking.
Kaolinite (/ ˈ k eɪ. ə l ə ˌ n aɪ t,-l ɪ-/ KAY-ə-lə-nyte, -lih-; also called kaolin) [5] [6] [7] is a clay mineral, with the chemical composition Al 2 Si 2 O 5 4.It is a layered silicate mineral, with one tetrahedral sheet of silica (SiO 4) linked through oxygen atoms to one octahedral sheet of alumina (AlO 6).
Terracotta, originally modelled in clay. Giant clay sculptures in Caruaru . Roses and seashells made of Paperclay (DECO) Industrial clay: a clay model of a BMW. Modelling clay or modelling compound is any of a group of malleable substances used in building and sculpting. The material compositions and production processes vary considerably.
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More recent trade began when a clay was needed to make tobacco pipes in the 16th and 17th century. [8] In 1771 Josiah Wedgwood signed a contract for 1,400 tons a year of ball clay with Thomas Hyde of Purbeck , enabling the production of thinner-walled ceramics.
Once a clay body has been kneaded and de-aired or wedged, it is shaped by a variety of techniques. After shaping it is dried and then fired. In ceramics , the making of liquid mud (called slip ) is a stage in the process of refinement of the materials , since larger particles will settle from the liquid .