I'm not 100%, but your coin looks to be of Tranquillina, she was the wife of Gordian III 238-244 AD. If the coin was complete the obverse would read: SABINIA TRANQVILLINIA AVG, and the reverse would be: CONCORDIA AVGG. Concordia seated patera and cornocupia. Coins of this empress are scarce an bring high prices in better condition.





















