Electrum is a native alloy of gold and silver in which the latter metal may be present in quantities of up to 40%. Electrum from the Ural mountains carries 20% copper. The color of electrum is pale yellow or yellowish-white and the name is derived from the Greek word mentioned in the Odyssey meaning a metallic substance consisting of gold alloyed with silver. The same word was also used for the substance amber, probably because of the pale yellow color of certain varieties.