A nice glossy, partially deficient piece.
Obverse: royal bust wearing crown, caracene and mantle, to the right, in the rim legend:
IOAN-III D G-REX-POL-M-D-L-R-P;
Reverse: crowned four-cornered crown with five trefoil fleurs, with jewels on the bails, a three-field escutcheon, with the coats of arms of the Crown of the Kingdom of Poland, the Grand Duchy of Lithuania and the Sobieski family coat of arms - Janina, between the coats of arms the mint mark C; under the crown the denomination mark VI, under the escutcheon the date 16-84; in the rim the legend divided by the coat of arms Jelita in an oval escutcheon:
GROS ARG SEX-REG POLONIAE;
