The main source of tin for isolation purposes comes from placer mining. Placer mining is the mining of alluvial deposits for minerals; it can be performed using water pressure, open-pit mining, or through excavation. The mineral cassiterite is a tin oxide mineral and is the mineral that is used most for tin isolation. Once ore that contains tin is collected, the tin isolation process begins with removing the ore through a reduction reaction using coal in a reverberatory furnace; in this furnace, the tin ore is heated in a private compartment that allows it to come in contact with the combustion gases of the coal but not the coal itself. The tin is removed easily from the ore in this manner, and it is believed that tin removal from ore through coal was used by ancient peoples. Since cassiterite is a tin oxide, SnO2, the only product from this type of isolation process using coal is pure tin and carbon monoxide.
