cuprum

Latin cuprum is a shortening of aes Cyprium — 'Cyprian metal' — because Cyprus was the ancient world's primary copper source. The island's name may come from Greek κυπάρισσος (kypárissos, cypress tree). The word entered Old English as copor and Middle English as 'copper.' The metal is named for its place of origin, and the place is named for its vegetation. Copper is, at three removes, named after a tree.

Copper was the first metal humans worked — hammered into shape as early as 9000 BCE in the Middle East. The Copper Age (Chalcolithic period, ~5000-3000 BCE) preceded the Bronze Age. When someone mixed copper with tin and produced bronze around 3300 BCE, the Bronze Age began and copper became an ingredient rather than a finished product. But copper continued to be used on its own — for coins, for roofing, for decoration — because of its malleability, its color, and its resistance to corrosion.

Copper pennies are not copper anymore. The US penny has been zinc with a copper coating since 1982. British pennies have been copper-plated steel since 1992. The copper content of a 'copper' coin has been declining for decades because the metal is worth more than the denomination. The word 'copper' in 'copper coin' is now a color description, not a material fact.

The green patina on the Statue of Liberty is copper oxide — the result of copper reacting with oxygen and moisture over decades. The statue was originally the color of a new penny. The green has become so iconic that most people do not know the original was brown-gold. The word 'copper' names both the new color and the old one, the original surface and the oxidized one. The metal changes. The word stays.