Galvan, judging by the quality of the reproduced details, reproduced probably from the casting of the medal of Mikołaj Zebrzydowski 1619 (Raczynski type #97 here).
This medal in original very rare, minted known from single pieces. The few pieces found on the market are usually old, probably still 17th century castings.
Copper, diameter ~51 mm, weight 7.3 g.
