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 known as green gold. The ancient Greeks called it gold or white gold, as opposed to refined gold and its colour ranges from pale to bright yellow, depending on the proportions of gold and silver. 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 gold content than the commonly circulating metal. Electrum was used as early as the third millennium BC in Old Kingdom of Egypt, sometimes as a coating to the pyramidions atop ancient Egyptian pyramids. 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 BC. 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. The name electrum is the Latinized form of the Greek word ἤλεκτρον, electrum was often referred to as white gold in ancient times, but could be more accurately described as pale gold, as it is usually pale yellow or yellowish-white in colour. The modern use of the white gold usually concerns gold alloyed with any one or a combination of nickel, silver. Electrum consists primarily of gold and silver but is found with traces of platinum, copper. The name is mostly applied informally to compositions between about 20-80% gold and 20-80% silver atoms, but these are called gold or silver depending on the dominant element. Analysis of the composition of electrum in ancient Greek coinage dating from about 600 BC shows that the content was about 55. 5% in the coinage issued by Phocaea. In the early period, the gold content of electrum ranged from 46% in Phokaia to 43% in Mytilene. In later coinage from these areas, dating to 326 BC, in the Hellenistic period, electrum coins with a regularly decreasing proportion of gold were issued by the Carthaginians. In the later Eastern Roman Empire controlled from Constantinople, the purity of the coinage was reduced. Electrum is mentioned in an account of an expedition sent by Pharaoh Sahure of the Fifth dynasty of Egypt and it is also discussed by Pliny the Elder in his Naturalis Historia. Electrum is possibly referred to three times in the Bible, in all three instances it is used to describe a type of glow seen in visions by the prophet Ezekiel. Electrum is believed to have used in coins circa 600 BC in Lydia under the reign of Alyattes II
Natural Electrum "wires" on quartz, historic specimen from the old Smuggler-Union Mine, Telluride, Colorado, USA.
Early 6th century BCE Lydian electrum coin (one-third stater denomination), one of the oldest known coins