Bronze is not a compound but a mixture of copper and another metal, and therefore has no chemical formula. Bronze commonly contains about 88 percent copper and 12 percent tin. Metal mixtures such as bronze are known as alloys.
Bronze is a brittle metal with a golden color. In the past it was distinguished from brass, which was an alloy of copper and zinc. A more modern usage is to call all copper alloys brass, with bronze as one type of brass.
Bronze has been known and used since antiquity. Ancient civilizations that are recognized as creating their own copper and tin alloys are said to have been part of the Bronze Age. For example, the Bronze Age of ancient Egypt began around 3150 BC.