 The name is mostly applied informally to compositions between about 20–80% gold and 20–80% silver atoms, but these are strictly 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 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 Phokaia to 43% in Mytilene.