Aurelian, 270-275. Antoninianus (Bronze, 24 mm, 3.51 g), Siscia, autumn 274-spring 275. IMP C AVRELIANVS AVG Radiate and cuirassed bust of Aurelian to right. Rev. CONCO[RDIA MILITVM] / XXIS Aurelian, on the left, laureate and togate, standing right, clasping hands with Concordia, on the right, veiled and draped, standing left. CBN 899-904. RIC 244. RIC V online 2364. Venèra 8375-440. A curious mint error with a reverse double-struck at 180° rotation, giving the appearance of a playing card. Somewhat smoothed and heavily double struck, otherwise, good very fine.


The inverted undertype on the reverse indicates that this piece was overstruck at a 180° angle on an antoninianus of the same type, though not from the same die. This suggests that two reverse dies of identical type were used in alternation to expedite the minting process. It is likely that at least four workers were involved: two alternating with different reverse dies of the same type, one placing the flans into the obverse die, and one striking with the hammer. The rapid succession of strikes resulted in this coin being struck twice - by both reverse dies - at an exact 180° rotation (the so-called 'Kraay-effect').