Looks more like Valentinian or Valens than Valerian. Reading the legends is hard on such unsharp pictures and its the only way to differ between Valentinian and Valens. The mintmark is possibly gone if I see that right.
Bronze coin (AE 3) minted at Siscia during the reign of VALENS between 367 - 375 A.D. Obv. D.N.VALENS.P.F.AVG. Pearl-diademed, dr. & cuir. r. Rev. SECVRITAS.REIPVBLICAE. Victory advancing left, holding wreath & palm. with r. RCS #4118 pg.347. RICIX #15b. DVM #49. LRBC #1374.