Natural Electrum "wires" on quartz, historic specimen from the old Smuggler-Union Mine, Telluride, Colorado
Early 6th century BCE Lydian
electrum coin (one-third stater
denomination), one of the oldest known coins
Cup with mythological scenes, a sphinx frieze and the representation of a king vanquishing his enemies. Electrum, Cypro-Archaic I (8th–7th centuries BCE). From Idalion
Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. It has also been produced artificially, and is often known as green gold. The ancient Greeks called it 'gold' or 'white gold', as opposed to 'refined gold'. Its colour ranges from pale to bright yellow, depending on the proportions of gold and silver.
The gold content of naturally occurring electrum in modern Western Anatolia ranges from 70% to 90%, in contrast to the 45–55% of gold in electrum used in ancient Lydian coinage of the same geographical area. This suggests that one reason for the invention of coinage in that area was to increase the profits from seigniorage by issuing currency with a lower gold content than the commonly circulating metal.
Electrum was used as early as the third millennium BCE in Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidions atop ancient Egyptian pyramids and obelisks. It was also used in the making of ancient drinking vessels. The first metal coins ever made were of electrum and date back to the end of the 7th century or the beginning of the 6th century BCE. For several decades, the medals awarded with the Nobel Prize have been made of gold-plated green gold.
The name electrum was also used to denote German 'silver', mainly for its use in making technical instruments.