AR25 - Severus Alexander L Ζ

Alexandria's billon tetradrachms of this period were struck under the Roman imperial administration of Egypt, which maintained a closed currency system — provincial coinage could not legally circulate outside Egypt, and foreign coinage could not circulate within it. The "L Ζ" in the designation is not a mintmaster's mark but a regnal year notation, here indicating Year 7 of Severus Alexander's reign, a dating convention unique to Alexandrian issues that allows precise dating otherwise impossible in most Roman provincial series.