Countermark

https://rpc.ashmus.ox.ac.uk/countermark/596 
GIC 468
swastika
square (one with slightly rounded edges) 
c. 7 x 7 mm 
Usually thought to have been applied at Gaza, which placed a mêm on its coins. However, at Gaza the form is different, and the single find at Antioch and the shared cmk 506 speak against an attribution to Gaza (but not decisively). 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 4264 Show 4264 2 1
RPC I, 4264 Show 4264 6 1
RPC I, 4279 Show 4279 7 1
RPC I, 4746 Show 4746 13 1
RPC I, 4264 Show 4264 14 1
RPC I, 4248 Show 4248 11 1
RPC I, 4248 Show 4248 12 1
RPC I, 4247a Show 4247 21 1