Nice patina. On the reverse there is a clear trace of metal sucking on the cross on the other side.
The reform carried out ~1364, in addition to the introduction of large half-shekels, initiated the minting of firchen. A denomination equivalent to 1/4 of a half-coin, which in Polish literature came to be known as a quarto. Like its quaternary counterpart, the issuance of firchen was a one-time event, and was interrupted by the shekel reform of 1380.