CRISPUS from Thessalonica VIRT EXERC...plan of Roman camp reverse.

[crispus]

The coin is not common and nice for type

Crispus
AE reduced follis, Thessalonica, 319
18 mm / 2,80 g

D N FL IVL CRISPVS NOB CAES, laureate and cuirassed bust right.
VIRT EXERC [Valor of the army] Plan of Roman camp, Sol standing in the middle raising right hand, holding globe in left, chlamys across left shoulder.
In exergue •TS•E•   
RIC VII Thessalonica 69 (R2) – Cohen 159

[Victor]

Nice example, these Thessalonica coins are tough to find in nice condition, especially with silvering. I wonder if they had a different minting/silvering process from other mints, as coins from this mint during this period frequently exhibit the same granular, rough surfaces.