No idea, Joe. You probably have seen this already, but Lionel
Holland "
Weights of
Caesarea Maritima" lists both dirhams and dinars in multiples of 1,2 5, 10, 20, 50, and 100 units; and divisions of 1/2, 1/3, 1/6, 1/12, 1/24 units. So, nothing like this one in there. He also has a square four nomismata marked N delta, #58, at 16.7 gm. I will keep an eye out for anything else.
Jimi