An alloy of copper and tin, sometimes containing small amounts of other elements in varying proportions such as zinc and phosphorus. Harder and more durable than brass and used extensively since antiquity for casting sculpture. Bronze alloys vary in colour from silvery hues to rich, coppery red. Different countries have different standards for the mix - and mixes also may vary from one foundry to another. In its molten form (ca. 1300'C), bronze is poured into the main channel or sprue of an investment casing surrounding a sculpture to produce the final cast piece of artwork.