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This is an ancient Roman silver Siliqua, of emperor Julian II, dating to 360 - 363 A.D.
Obverse: FL CL IVLIANVS P P AVG, "Flavius Claudius Julian, perpetual August (Emperor)", rosette-diademed, draped, and cuirassed bust right
Reverse: VOTIS V MVLTIS X "vows (prayers) on the fifth anniversary (of the emperor's rule), and for his (anticipated) tenth anniversary" in four lines within wreath.
This coin was minted at Arles (in France) with the mint mark being clipped away, however, the style of the portrait and lettering would indicate this mint. It had travelled across the English Channel, being discovered by a metal detectorist in Suffolk.
DATE: 360 - 363 A.D.
MINTMARK: SCON (Arles, France)
SIZE: 14.4mm dia
WEIGHT: 1.30 grams
Attribution: RIC VIII 219; RSC 163
PROVENANCE: Formerly in a private collection, Suffolk.