Diocletian AE Antoninianus. 287-288 AD, Lyons mint. 

Obv: IMP C DIOCLETIANVS AVG, helmeted, radiate, cuirassed bust left with 
 spear over shoulder

Rev: IOVI CONSER AVGG, Jupiter standing left holding thunderbolt & scepter, 
 eagle at foot, SML in ex, A to right.  

Unlisted in Cohen, rated scarce in RIC.

Found in Jura (Eastern France, near Lyon).
Weight 2.54 gm
Diameter 20mm

Contributed by an amateur French collector, December, 2003.