Gratian, 367-383 AD. Struck 378-383.
18 mm. 2.35 grams. AE3.
DN GRATIANVS PF AVG
VIRTVS ROMANORVM, Roma seated front, head left, holding globe and vertical scepter
Mintmark: ANTA, with control marks in the fields.
Techically, this type is not unique to Gratian since it was also issued in the name of Theodosius, but it is very rare for Theodosius and almost common for Gratian. The great majority are from the mint of Antioch.
The design is very much like the CONCORDIA AVGGG type which is common for Gratian, Valentinian II, and Theodosius, but this legend is nearly unique to Gratian.
This piece: RIC Antioch 50a, page 288.
Esty type 19: http://augustuscoins.com/ed/ricix/type19.html