Is This A Roman Coin Or A Replica (Id: Likely Fake Hadrian Denarius)

Difficult to say if it's genuine or not. Looks like Hadrian with Salus reverse. I not sure if it's an AE bronze or very toned dirty silver denarius.

You could measure it more precisely with a caliper and weigh it. The size and weight would help a lot to identify it as being a denarius or larger bronze coin like an asserion. If your measuring tape is in centimeters on the bottom then that would mean it's silver denarius size.

Compare it to Hadrian/Salus examples on sites like ascearch.info, coinarchives.com.

There were some bronze coins of Hadrian made on the edges of the empire that imitated the silver coins, some call them limes denarii. I don't know much about them. Here is one I saw on acsearch.info.

Might be a Hadrian denarius with the goddess Salus and her snake.
Looks a little like this one:
https://www.ebay.com/itm/2345238239...gad_source=1

Thx for mentioning the wax @jec as I was wondering why it was laid on so heavily on a silver coin.

Impossible to determine with any certainty by photos alone
I see no serious problems with it but the fakes are getting better all the time !
50/50
Not terribly valuable so not really worth great efforts to verify
You might show it to a dealer at a local coin show and ask for an opinion

The patina is totally fake. Is shows cleared around the relief areas in the reverse. If genuine the coin would have had to be all cleaned then regain patina but somehow miss those spots. But it has that false dirt in some spots there so it was not cleaned. That dark thing is not natural oxidized silver. I think it is paint.

The flan cracks in the edge look shallow. Rust can be applied to coins. The incrustations can be faked. Forgers really paint their coins some times. And looks like some paste of ash the obverse to hide the typical casting defects near the relief areas.

Because it looks dirty does not mean it is genuine. I am almost sure this is a disguised cast fake. But would need to see it in hand. Examine the cracks and teh edge.

I still cannot say from those photos. A sharp photo of the edge with the crack in the flan could help. Examine the cracks and see if they look natural or an incomplete cast reproduction. A cast can not reproduce the fine cracks or the surface of the stressed silver. But cast defects can be disguised with dirk. O the crack can have real corrosion products inside.

I can say I have a demarius found in a hoard, with silver corrosion products still in the surface. It looks nothing like what is in this obverse of this one.