How to Identify the Postumus Antoninianus

What Is the Postumus Antoninianus?

Postumus was a Roman general who broke away from central imperial authority in 260 AD to found the so-called Gallic Empire, ruling Gaul, Britain, and Spain independently until 269 while running a full Roman-style coinage and administration of his own. His antoninianus is notable for unusually high artistic quality compared to the crude central-empire coinage being produced by Gallienus in the same years.

Obverse Design and Inscriptions

The obverse shows a radiate, cuirassed bust right with an unusually robust, heavy-featured portrait style. The legend reads IMP C POSTVMVS PF AVG or close variants; some special issues depict him with attributes associated with Hercules, a deity he actively promoted.

Reverse Design and Inscriptions

Hercules-themed types are especially characteristic, reflecting Postumus's promotion of a Hercules cult tied to his Rhine frontier campaigns. Other common reverses include Moneta standing with scales and cornucopia, Fides Militum, Salus, Neptune, and Serapis.

Size, Weight, and Metal

The coin measures roughly 21-23mm and weighs about 3-4 grams, generally better silvered and better struck than contemporary central-empire issues of the same years.

Mint Marks and Where to Find Them

Coins were struck at Gallic mints, primarily Cologne and Trier, identifiable more by die style and portrait treatment than by an explicit mint letter in the exergue.

Telling It Apart from Similar Coins

Distinguish Postumus from the other short-lived Gallic Empire rulers who followed him - Laelianus, Marius, Victorinus, and the two Tetrici - by the legend name, since all share a broadly similar radiate portrait style. Numerous "barbarous radiate" imitations of Postumus and his successors also circulated at the time; these unofficial copies are smaller, cruder, and often carry blundered or illegible lettering, and are collected as their own distinct category rather than treated as official issues.

Judging Condition at a Glance

Check the radiate crown's points, the cheek, and the reverse figure's raised limbs for wear, using the same criteria as other well-struck third-century antoniniani.

Authenticity Red Flags

Because official Postumus coins are generally well made, a crude, poorly centered strike more likely indicates a period "barbarous" imitation than a modern fake. Modern casts also exist, however, and show the usual seam and porous-surface signs regardless of which category a rough-looking coin might otherwise suggest.