CARAUSIUS, Romano-British Usurper 
AD 286-293
AE Antoninianus. 2.49g, 20.4mm
MINTED: Uncertain British mint, AD 286-293
REF: RIC -; cf. Normanby 1590
OBVERSE: [IMP CARAVSIVS] P F AV, radiate, draped and cuirassed bust right.
REVERSE: PAX AVG, Pax standing left, holding olive branch and sceptre.
 
Provenance:
Ex Richard Plant Collection
Reverend Richard Plant (1928-2000) was a lifelong coin collector and the author of the books "Greek Coin Types and Their Identification", "A Numismatic Journey Through the Bible", and his most famous work, "Arabic Coins and How to Read Them", for which he won the Royal Numismatic Society's Lohkta Memorial Prize in 1975.

Notes:
Green patina; roughness. 
 
Historical Notes:
Carausius was a naval commander under Emperor Maximianus who had been tasked to rid the English Channel of pirates around AD 286.  Suspected of keeping captured treasure for himself, his execution was ordered, but Carausius instead revolted and declared himself Emperor in Britain and northern Gaul.  With his fleet of ships, four legions of troops, and other foreign soldiers and mercenaries attracted to his banner, Carausius managed to stay in power for seven years, until he was betrayed and assassinated by his own finance minister, Allectus, in AD 293.