I picked up this scarce tetradrachm struck in Antioch by Q. Caecilius Bassus (year 3; 47 BC) in the name of Philip I, as a possible fun cleaning job. The gunk on the obverse was a lot harder than on the other silver coins I've cleaned in the past, so I had to use a greater concentration of ammonia than I normally do. Unfortunately there was some more pitting revealed under the face gunk, but I'm definitely satisfied with the results. (apologies for the different color tones I only had incandescent in the first set of photos then I had already bought fluorescent by the time of the second set)
Glad you were able to clean it up. I believe yours is actually year 6(ς) 44/43 BC. Gamma is year 3. That also places it under Gaius Cassius Longinus. Not my coin.
Is the man on obverse Gaius Cassius Longinus. Is this a Greek or Roman coin? Under which name shall I search on Wildwinds. I think I have a similar one.