Tetradrachm - Maximianus Herakles, Alexandria

By 290–291, the Alexandrian mint was producing billon tetradrachms at a fraction of their earlier silver content — the alloy had been debased so aggressively over the preceding decades that these coins were effectively bronze with a surface wash. Maximianus had been elevated to co-emperor by Diocletian in 285, and Egypt's mint responded by integrating his portrait into the regnal year sequence already established for the joint reign, treating the new Augustus as a continuation rather than a rupture.

The Emmett 4130 attribution places this within a tightly documented sequence for Year 6 of the era reckoning used at Alexandria.