Cast iron is an alloy of iron that contains 2-4% carbon and trace amounts of manganese and silicon and is most commonly associated with gray iron. Cast iron is formed by smelting iron ore and mixing it with scrap metals and other alloys. The liquid mixture is then poured into molds and allowed to cool and solidify. Cast iron is more rigid, more brittle, and less malleable than wrought iron, making it perfect for products with complex shapes.