I was attracted to this coin by the portrait style and bought it without having done any research on it. It turns out to be quite rare and hold some historical interest. It is issued as he emerged from his abdication by Maximinus II Daia (see notes below).
Follis
Obv:- IMP C M AVR VAL MAXIMIANVS P F AVG, Laureate, draped and cuirassed bust right
Rev:- GENIO IMP-ERATORIS, Genius standing left holding patera and cornucopia
Minted in Antioch (_ Theta / E //ANT Dot). Early to Later A.D. 309
Reference:- RIC VI Antioch 112c (R) (Citing Oxford)
6.39 gms. 26.19 mm. 0 degrees.
From RIC Notes "A very remarkable innovation, peculiar to this issue, is the reappearance of Herculius (with the long legend Imp C M Aur Val Maximianus P F Aug matching those of Galerius and Licinus, and with cuirassed bust) on rare coins with Genio Imperatoris; this is parallelled at the same time (see RIC VI page 656). Expelled from Italy c. April 308, and rejected at the Carnuntum conference in November 308, Herculius had received ample share in the coinage of Constantine's mints, and it seems that Maximinus (now antagonistic to both Galerius and Licinius) may have been momentarily willing to demonstrate his hostility by including the name of the man who might still play and anti-Galerian part in the west."

Martin