Copper

Evidence for the use of copper in the service of man dates back to the Chalcolithic period; the transitional period between the Stone Age and Iron Age. Along with gold, copper was one of the first metals to be used by humans. This may be because, unlike iron and other metals that have to be extracted from ores, copper and gold can be found in their metallic form in nature, so prehistoric man may have been confronted with lumps of this red-gold metal buried in the ground. Archaeological findings suggest that the earliest use of this naturally-occurring copper was in the 9th century BC in modern-day Iran. It seems copper smelting was not discovered until later, occurring independently in several places around the world from about the 5th century BC.

Originally this sample would have been a bright pinky-gold colour but has tarnished over time to a deep, rich reddish-orange with a slight verdigris tide-mark, and with traces of fingerprints on the surface, probably as a result of coming in contact with acids in the skin. 

Copper is naturally biostatic and antibacterial, and for that reason it is often used in pipes that carry drinking water to our taps, on doorknobs in hospitals, and in antifouling paint on ships to protect against barnacles and mussels. Like most substances, in high enough concentrations it can be toxic to humans, but small amounts of copper are an essential trace nutrient for plants and animals. Copper is also very ductile and electrically conductive, and is often used in electrical wiring. As the scarcity and therefore price of copper has increased, metal theft has become more of a problem, probably coupled with the fact that copper is a very recognisable material. The next time your train is delayed, it might be because someone’s stolen the copper cable from the tracks.