Fire Clay
Fire Clay, a variety of clay that can withstand intense heat. In general, it is any clay that can withstand temperatures of 2,900 F. (1,590 C.) or higher. It must also be able to withstand rapid temperature changes and the chemical action of slag and hot gases. Fire clay is used in making firebrick. Both fire clay and firebrick are used to line blast furnaces, glass furnaces, fireboxes, kilns, and crucibles.
Fire clay is low in materials such as iron, lime, and magnesium, which promote melting. It is rich in silica and alumina. Fire clay is commonly found in association with coal.