The term "fire clay" refers to a group of refractory clays used in the production of ceramic, particularly fire brickwork. Fire clay is defined by The Department Of Environment as a mineral aggregate formed of hydrous aluminium silicate,i.e, Al2O32SiO2H2O. It can occur both with and without free silica.

Because electric pottery kilns are easily obtainable and simple to build, electric kiln fire is one of the most popular ways for firing clay. Coal mines are a frequent site of fire clay. Fire clay is a form of clay that is used to make heat-resistant clay products, such as volumetric flasks used in the mining industry.