The process of smelting changes tin ore into metal.
Tin and copper are mined as ores. Smelting is the process of reducing metal ores to metal. Tin ore is processed to create tin concentrate which is a fine black powder. The fine black tin concentrate is heated with carbon and is reduced to form the metal tin. No-one knows for certain how this process was discovered but it was probably by accident. Once the tin concentrate was smelted into a hot molten metal, it could be cast into an ingot and stamped with a smelters mark. Tin concentrate was not smelted at Geevor. By 1732 a tin smelting works had been established at Trereife near Penzance and the tin concentrate from the St Just mines, including Geevor, was smelted here or later at the Chyandour smelters also in Penzance.