Clay

Clay is a fine-grained natural earth material that becomes plastic when wet and hardens when dried or fired. Its particles are chiefly clay minerals, though natural clay also contains varying impurities.

Clay minerals: A group of fine-grained phyllosilicate minerals that form the main components of many clays. Their layered structures give clay its characteristic plasticity and water interaction.
Adsorbed water: Water molecules held on a solid surface by intermolecular forces rather than incorporated into its crystal structure. Water on clay-particle surfaces lubricates movement and contributes to plasticity.
Pottery: Vessels and other objects formed from clay and hardened by drying or firing. Pottery is a direct use of clay's ability to hold a shape and harden.
Terracotta: A porous, usually reddish earthenware made from fired clay. It is a recognizable clay body used in sculpture, vessels, and architectural elements.
Landslide: The downslope movement of rock, soil, or debris under gravity. Water-sensitive clay layers can fail and trigger destructive slides.
Kaolinite: A common clay mineral composed of stacked sheets of silica tetrahedra and alumina octahedra. It is a principal mineral in kaolin clay and many ceramic bodies.
Drying shrinkage: The reduction in dimensions of a wet material as it loses water during drying. Clay contracts as water leaves spaces between its particles, sometimes causing cracks.
Brick: A rectangular building unit commonly made from clay and hardened by firing. Fired clay bricks turn an abundant earth material into durable masonry.
Porcelain: A dense, often translucent ceramic made by firing a refined body at high temperatures. Its refined ingredients and firing distinguish porcelain from ordinary clay-rich earthenware.
Quick clay: Sensitive marine clay that can lose much of its strength when remolded. Its sudden strength loss makes some clay-rich slopes exceptionally hazardous.

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