Countermark

https://rpc.ashmus.ox.ac.uk/countermark/1223 
GIC
ΗΡΑ(Κ)
rectangular 
9 x 3.5 mm 
The countermark likely refers to a city by the name Heraclea, of which there was one in Bithynia, Caria and Macedon 

Coins with this countermark

Number Image TypeNumber CoinNumber VolumeNumber
RPC I, 1657 Show 1657 29 1
RPC I, 1657 Show 1657 34 1
RPC I, 1657 Show 1657 40 1
RPC I, 1657 Show 1657 41 1
RPC I, 1656 Show 1656 121 1
RPC I, 1656 Show 1656 126 1
RPC I, 1656 Show 1656 94 1
RPC I, 1656 Show 1656 96 1
RPC I, 1656 Show 1656 111 1
RPC I, 1657 Show 1657 30 1
RPC I, 1656 Show 1656 128 1
RPC I, 1657 Show 1657 46 1
RPC I, 1656 Show 1656 133 1