Gratian, AR three-quarter siliqua (half argentius), Trier. 17mm, 1.64g. 378-383 AD. 

DN GRATIA-NVS PF AVG, pearl diademed, draped, cuirassed bust right.
PERPETVETAS, Phoenix, nimbate, standing left on globe
Mintmark TRPS.

RIC IX Trier 56a; RSC 27+.
Very rare (R3)

Contributed by Dr. Hubert Lanz, auction November 2000, 
Added July 2011.