Modern COPY of an ancient Greek coin (tetradrachm) from Acanthus

Modern COPY of an ancient Greek coin (tetradrachm) from Acanthus as follows:
Obverse: Lion attacking bull, stylised acanthus flower below
Reverse: Quadripartite incuse square
28mm diameter, appears to be made from good quality silver, 16.45gm.
Purchased in Athens more than 20 years ago.