Fireclay bricks are made of various fire clays and calcined chamotte, and are divided into three categories: General fireclay bricks, hard fireclay bricks, and special fireclay bricks. General fireclay bricks find the widest application among various kinds of refractory bricks. Hard fireclay bricks are manufactured by molding carefully selected materials under high pressure and by thoroughly firing those molding. They are, therefore, suited for use in high-temperature, high-pressure operating furnaces such as blast furnaces. Special fireclay bricks have low thermal expansion coefficients and particularly high resistance to spalling and wear.