AR24 - Antoninus Pius L Ε

The regnal year marker L Ε — year five of Antoninus Pius — places this issue squarely in 141/142 AD, a period when the Alexandria mint was producing billon tetradrachms at high volume to service Egypt's closed currency system. Egypt operated as a monetary isolate under Roman rule: foreign coins were confiscated at the border and exchanged for local issues, a policy that makes Alexandrian tetradrachms essentially self-contained as a series. The billon content had already been degraded well below the old Ptolemaic standard by this point, a slide that would continue under successive emperors.