Aureolus was Master of the Horse, commander of the Roman cavalry, under Gallienus. He was responsible for the defeat of the Macriani usurpers and was left in charge of the West while Gallienus was occupied with the East. He later revolted against Gallienus who besieged him at his headquarters at Milan (Mediolanum). During the siege, Aureolus, although declared Augustus by his troops, announced his loyalty to Postumus and issued coins from the mint at Milan in the name of Postumus. Coins issued during this revolt tend to be small and crude even by the reduced standards of that period. They are distinguished from other coins of Postumus by the use of an officina (workshop) letter (P, S or T) in the reverse exergue and by a strong tendency (there are exceptions) to the mention of the cavalry (EQVITVM or AEQVITVM) in reverse legends (Source: Doug Smith)

Grade: F+/VF- strong traces of the original silvering
Material: AE/BI silvered
Weight: 3.42 g
Diameter: 21,50 mm
Ref.: Cunetio 2483/2492. Elmer 613
 
Obverse: IMP POSTVMVS AVG Radiate, draped and cuirassed bust of Postumus to right
 
Reverse: CONCORD EQVIT ,Concordia standing front, head to left, placing her right foot on prow and holding patera in her right hand and rudder set on globe with her left, S in exergue