Iron with a high carbon content (above 2%). Identical, in most cases, to pig iron, it is easily cast to almost any shape and melts at a lower temperature to other type of iron and steel. Traditionally melted in a cupular furnace (a tall cylindrical structure but much smaller than a blast furnace).

Cast iron is extremely hard and brittle. Machining is difficult and it is easily shattered, revealing its crystalline structure. Chilled cast iron is even harder and is produced by cooling the castings to increase the speed at which the iron solidifies. Cast iron is still is wide use for numerous casting, from drains covers through to engine blocks and water pipes. Can be grey, white or malleable.