First double bust type Roman silver I have seen.
Sent to Mark Lehman for an ID. Mark replied:

Very interesting – this is Marcus Antonius – Marc Antony – and Octavian (later to be Augustus) – an issue from Ephesus in the spring-summer of 41 BC – before the two of them had fallen out and while they were two legs of the triumvirate – along with Pompey.
This is a HIGHLY desirable coin in almost any condition, but this is in pretty good shape. The “granular” area, I’m afraid, looks a lot like a shovel-mark – but that’s one of the almost unavoidable risks of MD (or really, any) digging style.
I would advise the owner to seek professional conservation – or to leave it completely as-found until some sophisticated and professional cleaning techniques can be brought to bear.
You may hear talk about the “historicity” of a coin – this one is from quite near “ground zero” for the true beginning of the Roman Empire as we know it.
My congratulations to the digger. It might not have the market potential of an aureus, but it’s an important historical document nonetheless. Mark

Obverse: M ANT IMP AVG III VIR R P C M BARBAT Q P (MP & AV are ligate) Bare head of Marc Antony right
Reverse: CAESAR IMP PONT III VIR R P C. Bare head of Octavian, right