Greek bronze helmet, mid 4th–mid 3rd century BC.
Egyptian cat, thought to have been sculpted and cast in bronze at least 4,000 years ago.
Bronze alloys are made primarily from two metals, tin and copper. In the metallurgy of the Bronze Age bronzes could have been made – and probably were – in a number of ways. Tin occurs mainly in nature as an oxide called cassiterite (top), which is often found in rivers or lakes as an alluvium deposit. Copper also occurs as many kinds of ores, as well as the 'ready-to-use' native metal (bottom). In some regions, a Copper Age preceded the Bronze Age.
Bronze is thought to have been the first metal alloy ever made, although it was probably produced originally by the accidental smelting of mixed ores of copper and tin. It is an alloy of copper and no more than 30% tin, known since the 4th millennium BC, and used then for tools and weapons, now for machine parts and marine hardware. Statues are often cast in bronze. It is a hard, strong alloy with good corrosion-resistance (the patina formed in air is protective).