Help Identifying Roman Coin

I think it is of Augustus with Artemis reverse, Ephesus mint. Ephesus issued a lot of coins showing Artemis (Diana), tourists visit the remains of Artemis' temple there. The reference number is RPC 2588 though there are variations. If you go to Roman Provincial Coinage site they have a database you can do a search for fuller description and more examples.

Turkey, Egypt, Greece and other nations have laws making it illegal to export ancient coins and artifacts. Years ago it was legal, but not now. People can be arrested trying to take ancient coin out of the country. There are tourist shops in Turkey that sell modern fake ancient coins, most are cast.

If the white/green substance on the coin is hard, stable, not powdery, then that's good. If it's powdery then it's verdigris and should be treated with something like Verdicare. You can do a search about treating verdigris on ancient coins.

I have a coin like yours, here it is. Also is a pic of fake coins being sold close to Ephesus some years back. The pic came from an article about visiting Ephesus.

It was struck during the reign of Augustus (27BC-14AD), as I said it was made in Ephesus, go to RPC for more details. Value depends a lot on condition, yours is pretty worn. You could look on Vcoins.com and other sites like ancient coin sold auctions and ebay sold listings. But you may not find this specific coin type, many different types were made. I'm guessing yours is in the $25-$45 range. Just because something is old or scarce does not mean it's worth a bunch. If in better condition yours would be worth a lot more.

Here is link to RPC database of Ephesus coins, 67 pages of them. I'm pretty sure yours is number 2588.

https://rpc.ashmus.ox.ac.uk/search/...hesus&page=2