Plaster, unfortunately. I could not find a better picture. The piece is of a coin minted around 400 BC in Olympia, the site of the Olympic Games in the region of Elis. On the left is the head of Zeus of Elis; on the right the head of an eagle, Zeus familiar. In my opinion the expression on the eagle's face is one-of-a-kind. On the maple leaf below are the letters DAI for Daedalus, perhaps a signature, which we find however on other coins from Elis. On the reverse is a stylized flash of lightning with with the letters F - A for Elis. In my opinion, this eagle's head is the most beautiful animal depiction in all of Greek numismatic art.