 The earliest known electrum coins, Lydian and East Greek coins found under the Temple of Artemis at Ephesus, are currently dated to the last quarter of the 7th century BC (625-600 BC).Electrum is believed to have been used in coins c.600 BC in Lydia during the reign of Alyattes.Electrum was much better for coinage than gold, mostly because it was harder and more durable, but also because techniques for refining gold were not widespread at the time.