Countermark

https://rpc.ashmus.ox.ac.uk/countermark/664 
GIC 534
ΔΧ or ΧΔ
oval 
8 x 6 mm 
Applied at Anchialus or Apollonia Pontica. 4 chalcoi? 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC IV, 4533 (temporary) Show 2654 7 4.1
RPC IV, 4532 (temporary) Show 2653 3 4.1
RPC IV, 4532 (temporary) Show 2653 4 4.1
Show 191
Show 265
RPC IV, 6952 (temporary) Show 2651 5 4.1