
On the observe of the coin is the head of a bull with a human face. Behind the head is a small seal, symbol of the city. On the reverse are four incuse punches.
Electrum, a gold and silver alloy occurring naturally in the region, was transformed into money by the Greeks, although the alloy's ambiguous nature soon led the authorities to assay it and mark the individual pieces. Towards the end of the Archaic period the main centres issuing electrum coins were, apart from Phocaea, Mytilene on Lesbos, Cyzicus and Miletus.