AR24 - Antoninus Pius L Ζ

Year 7 of Antoninus Pius's reign — the regnal year encoded in the obverse legend — places this tetradrachm within the early stability of a reign that would run an exceptional 23 years without military campaign or dynastic crisis. Alexandria's billon tetradrachm was the monetary backbone of Roman Egypt, a closed currency system that barred foreign coin and forced all commerce through the imperial mint at Alexandria. The silver content of these coins had been declining steadily since the Neronian reforms of the 60s AD, and by the Antonine period the alloy was a fraction of what provincial coinages elsewhere might carry.