Countermark

https://rpc.ashmus.ox.ac.uk/countermark/901 
GIC 771
denominational mark Γ
triangular 
4 x 4 x 4 mm 
on coins of Heracleia and Tium 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC VII.2, 2070 Show 2070 6 7.2
RPC X, — (number not assigned), type ID 87533 Show 2405 7 10