Constantius II 19mm AE3. 350 AD. 

Obv: DN CONSTANTIVS PF AVG, pearl diademed, draped, cuirassed bust right
Rev: FEL TEMP REPARATIO, radiate phoenix standing right
on rocky mound. 

Mintmark: Delta SIS(symbol 4 = a Y shape) 

Courtesy of Roma Numismatics, Feb, 2010