Copper beads over 10,000 years old have been excavated in northern Iraq and are presumed to have been made from natural copper, as such lumps of metal are sometimes found. Copper was widely used in ancient times as bronze, an alloy of copper and tin, and was used to make knives, coins and tools. In China it was used as a platoon bell.
Copper is not difficult to extract from its ores, but the deposits that can be mined are relatively scarce. Some, such as the copper mines in Falun, Sweden, were a source of great wealth from the 13th century onwards. One method of extracting this metal is to roast the sulphide ore and then separate the copper sulphate it forms with water. Afterwards flowing over the surface of the iron filings the copper precipitates, forming a thin layer which is easily separated.
