An ingot is a solid block or bar of metal that has been cast from a molten state into a standardized shape and size for ease of storage, transport, trading, or further processing. In the context of gold mining, the term ingot (also referred to as a doré bar at the mine production stage) specifically describes a semi-refined bar of gold and silver alloy that is produced at the mine site or regional smelter by smelting the gold-bearing concentrate, precipitate, or loaded carbon produced during the leaching and recovery circuit. Gold doré bars typically contain between 60% and 95% gold, with the remainder consisting primarily of silver and trace impurity metals, and are subsequently transported to accredited precious metals refineries for further processing to achieve London Bullion Market Association (LBMA) Good Delivery standard, which requires a minimum gold fineness of 99.5%. In diamond mining and iron ore mining, the term ingot is less directly applicable, as diamonds are a mineral gem product and iron ore is typically exported as a bulk crushed, screened, or pelletized product rather than a smelted metal. However, in the downstream processing of iron ore into pig iron or steel, ingot casting has historically been an important step in the steel production process, though it has been largely superseded by continuous casting in modern integrated steel plants. In bauxite mining, the Bayer process produces alumina (aluminum oxide), which is subsequently smelted via the Hall-Héroult electrolytic process to produce aluminum metal, which is then cast into aluminum ingots of standardized dimensions for use in fabrication and manufacturing industries. Gold ingots remain a globally recognized store of monetary value, traded on international commodity exchanges and held in the reserves of central banks worldwide.
