I've had this for years. I have a written note which describes it as follows: "Egypt under Roman rule of Maximianus (AD 286-305),Billon Tetradrachm of Year 4 (289/90) from the Alexandra Mint"
But when I check what that coin looks like,("ROMAN PROVINCIAL - Egypt, Alexandria, Maximian, Tetradrachm, Yr. 4 (288/9 A.D.)") it isn't the same.
What I find is that it matches "ROMAN PROVINCIAL - Egypt, Alexandria, Diocletian, Tetradrachm, Yr. 6 (289/90 A.D.)"
Is that the correct ID? I see they were co-emperors. Any explanation of the connection between the two would help.