Clay

Clay is a type of fine-grained natural soil material containing clay minerals, which are hydrous aluminium phyllosilicates such as kaolinite. 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. Clays develop plasticity when wet but can be hardened through firing, which is why clay is the working material of the potter and of the wheels, kilns and tools used in pottery.