Natural or artificial alloy of gold with at least 20% silver, used to make the first known coins in the Western world. Most natural electrum also contains copper, iron, palladium, bismuth, and perhaps other metals. The colour varies from white-gold to brassy, depending on the percentages of the major constituents and copper. The first Western coinage, possibly begun by King Gyges of Lydia (7th century BC), consisted of irregular ingots of electrum bearing his stamp as a guarantee of negotiability at a predetermined value. See alsocoinage.