Venetian Crete coin with countermark

[aidab]

This coin is, I guess, an venetian II soldi coin for CANDIA (Crete), but it has been countermarked with an "S" in one side and a number of two figures I can not disrinct very well in the other side (may be it is a 20 or 30 )
Has anyone idea for what or where this coin was countermarked ?

[mumde]

Crete was in the possession of the repubic of Venice. In 1648 the Turks tried to capture the island, and they started to besiege several fortresses on the island. In 1669 Heraklion was captured. Some fortresses held out for some more years, even until 1715.
Such copper coins as yours are known with several counterstamps, but only two of them can be interpreted as giving the names of Venetian commanders. With the other counterstamps one cannot be certain what they mean. The counterstamp on the reverse of your coin is most probably GB which might stand for the fortress Grambusa. The S could mean the name of the commander of that fortress. But this is just conjecture.
The coins and the counterstamps are catalogued in: Prokisch, Emmerig u. a., Repertorium zur neuzeitlichen Münzprägung Europas XVIII, S. 214.