Constantine I AE Light Follis. 2.61 gr, 19.37 mm. Trier. 316 AD.  

Obverse: CONSTANTINVS PF AVG, laureate and cuirassed bust right.  Reverse: MARTI CON-SERVATORI, Mars, helmeted, in military dress, cloak 
spread, standing right, holding reversed spear, left hand resting on shield; 
T-F across fields, mintmark BTR. 

Unlisted bust type for the series with this obverse legend and mintmark. 

RIC VII Trier 113 var.

Courtesy of TimeLine Originals (www.time-lines.co.uk), March, 2011