The Antoninianus was a Roman silver coin introduced by the emperor Carus in 214 CE during the reign of his son Carinus. Initially, it was meant to be a more valuable successor to the denarius, with the intention of increasing the Roman empire’s coinage output to address economic pressures. The Antoninianus was roughly worth two denarii and was often marked with the legend “M. Ant. Aug.”, referring to the emperor’s full title, “Marcus Antonius Augustus,” or simply “Antoninus” in later issues. However, the Antoninianus’ value rapidly depreciated as time went on, largely due to the increasing use of lower-quality metals in its production, which led to inflation and a decrease in its silver content.

The coin was characterized by its larger size compared to the denarius, but this was not accompanied by a corresponding increase in the actual amount of precious metal. Initially, the Antoninianus contained a significant percentage of silver (around 50% during its early years), but over time, especially during the later part of the Crisis of the Third Century (235–284 CE), the silver content sharply decreased, and it was gradually debased with copper. This debasement reflected the economic struggles of the Roman Empire during the period, with emperors attempting to maintain their military and administrative apparatus in the face of continuous pressures from invasions, civil war, and fiscal crises.