Countermark

https://rpc.ashmus.ox.ac.uk/countermark/70 
GIC 664
Α in circular punch
circular 
6.5 mm 
applied to 3rd C coins of Mallus. Possibly a denominational mark. The coins countermarked A at Antiphellus (660) and Adana (663) are roughly the same size 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC IX, 1437 Show 1437 18 9
RPC IX, 1435 Show 1435 20 9
RPC IX, 1434 Show 1434 4 9
RPC IX, 1436 Show 1436 3 9
RPC IX, 1435 Show 1435 4 9
RPC VIII, — (number not assigned), type ID 2193 Show 2329 2 8
RPC VIII, — (number not assigned), type ID 2201 Show 2328 12 8
RPC X, — (number not assigned), type ID 60494 Show 4061 5 10
RPC X, — (number not assigned), type ID 60492 Show 4059 23 10
RPC X, — (number not assigned), type ID 60492 Show 4059 8 10
RPC VIII, — (number not assigned), type ID 2201 Show 2328 7 8