Aetna, Sicily, AR tetradrachm. 17.23 gr, 26mm. 476-431 BC. 

Obv: AITNAION, head of the satyr Silenos, bald and bearded,
 right, with pointed horse’s ear, and wearing a wreath of 
ivy wreath, beetle below. 

Rev: Zeus Aitnaios seated right on ornamented throne 
covered with a panther’s skin, himation draped over 
his left shoulder and arm, holding thunderbolt in 
extended left hand and a knotted vine staff bent into 
a crook at the top in his right hand; to right a 
pine tree with an eagle perched on top.

Collection Lucien de Hirsch, Bibliothèque royale de 
Belgique, Brussels

The Aetna Tetradrachm is one of the rarest Greek coins 
known, and a spokeswoman for the museum has placed a
 conservative estimate of its value at more than $3 million. This Aetna Tetradrachm is the only one of its series ever discovered.

Hill, Coins of Ancient Sicily, P. 74 and Pl. 4, 13.