Probus silvered AE Antoninianus, Mars reverse

Probus (276-282 AD). Silvered AE Antoninianus (22-23 mm, 4.08 g), Ticinum, AD 279.
Obv. IMP C PROBVS AVG, Radiate and mantled bust to left, holding eagle-tipped sceptre.
Rev. MARTI PACIF, Mars advancing left, holding branch, spear and shield; I in left field, QXXI in exergue.
RIC 508.

Almost fully silvered and extremely fine.