The bloomery was the earliest form of smelter capable of smelting iron. Coal was used to run furnaces for the smelting of metal ore. Silver is commonly extracted from ore by smelting or chemical leaching. Coke is used to reduce iron ore into iron (smelting). Cobalt can also be leached from the slag of copper smelting. Iron ore was also used as a flux in the smelting of copper. Alcoa Corp. would continue the business of mining, smelting, and refining of raw aluminium. Heating this material with silica in flash smelting removes much of the iron as slag. These furnaces were used for direct smelting to steel. Electrolytic aluminium smelting also uses graphitic carbon electrodes. The most prominent example is that of iron ore smelting. Anthracite for iron smelting was later displaced by coke. The emerging industrial period commenced around the development of copper smelting in the Swansea area. The former can be removed by washing the ore prior to smelting. Early steel was made by smelting iron.