Dated Caesar Constantius Roman Egypt Alexandria billon silver tetradrachm coin.
Struck on thick flan for Constantius during his first (letter A on coin) Alexandrian year = 292/3 CE.
Obverse: laureate bust of Constantius facing right.
Reverse: Eagle standing right, palm on wing, no wreath.
Emmett 4178/1 rated as R4 (R5 highest rarity).
Certified by NGC to XF, nice brown patina.