thumb|Natural electrum "wires" on quartz, historic specimen from the old Smuggler-Union Mine, [[Telluride, Colorado, USA]]
thumb|The [[Pactolus river, from which Lydia obtained electrum for its early coinage]]
thumb|Electrum [[Phoenician metal bowls|Phoenician bowl with mythological scenes, a sphinx frieze and the repre­sentation of a king vanquishing his enemies, Cypro-Archaic I, from Idalion, 8th–7th centuries BC (Louvre, Paris)]]
thumb|Brooch with a griffin [[protome, from the necropolis of Kameiros, Rhodes, (Louvre)]]
Electrum is a naturally occurring alloy of gold and silver, with trace amounts of copper and other metals. <!-- The ancient Greeks called it "gold" or "white gold", as opposed to "refined gold". -->Its color ranges from pale to bright yellow, depending on the proportions of gold and silver. It has been produced artificially and is also known as green gold, though the color is more pale yellow than green.
Electrum was used as early as the third millennium BC in the Old Kingdom of Egypt, sometimes as an exterior coating to the pyramidia atop ancient Egyptian pyramids and obelisks. It was also used in the making of ancient drinking vessels. The first known metal coins made were of electrum, dating back to the end of the 7th century or the beginning of the 6th century BC.
Etymology
The name electrum is the Latinized form of the ancient Greek word ἤλεκτρον (ḗlektron), meaning amber or an alloy of gold and silver. Electrum was often referred to as "white gold" in ancient times.
Composition
Electrum consists primarily of gold and silver but is sometimes found with traces of platinum, copper, and other metals. The term is mostly used informally for compositions containing 20–80% gold and 80–20% silver, but these are strictly called gold or silver, respectively, depending on the dominant element. Analysis of the composition of electrum in ancient Greek coinage dating from about 600 BC shows that the gold content was about 55.5% in the coinage issued by Phocaea. In the early classical period, the gold content of electrum ranged from 46% in Phocaea to 43% in Mytilene. In later coinage from these areas, dating to 326 BC, the gold content averaged 40% to 41%. In the Hellenistic period, electrum coins with a regularly decreasing proportion of gold were issued by the Carthaginians. In the later Eastern Roman Empire, which was controlled from Constantinople, the purity of the gold coinage was reduced.
History
thumb|[[Lydia#First coinage|Lydian electrum coin (one-third stater), one of the oldest known coins, early 6th century BC]]
thumb|Electrum coin of the [[Byzantine Emperor Alexius I Comnenus, ]]
thumb|upright|A mummified male head covered in electrum, from [[Ancient Egypt, Roman period, 2nd century AD (Musée des beaux-arts de Lyon)]]
Electrum is mentioned in an account of an expedition sent by Pharaoh Sahure of the Fifth Dynasty of Egypt. It is also discussed by Pliny the Elder in his Naturalis Historia.
Early coinage
The earliest known electrum coins, Lydian coins and East Greek coins found under the Temple of Artemis at Ephesus, are currently dated to the first half of the 7th century BC (c.650 BC). Electrum is believed to have been used in coins in Lydia during the reign of Alyattes.
In Lydia, electrum was minted into coins weighing , each valued at stater (meaning "standard"). Three of these coins—with a weight of about —totaled one stater, about one month's pay for a soldier. To complement the stater, fractions were made: the trite (third), the hekte (sixth), and so forth, including of a stater, and even down to and of a stater. The stater was about to . Larger denominations, such as a one-stater coin, were also minted.
Because of variation in the composition of electrum, it was difficult to determine the exact worth of each coin. This problem hampered widespread trading, as the intrinsic value of each electrum coin could not be easily determined. 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.
These difficulties were eliminated when the Croeseids, coins of pure gold and silver, were introduced.