Help Identifying and Evaluating a Roman Coin

Hello everyone,
I recently came across an old coin that I believe might be Roman, and I would really appreciate any help in identifying and evaluating it.

I’ve attached photos of both sides of the coin.

One side features what looks like a helmeted head (possibly Roma or Minerva?)

The other side shows the word "ROMAN" surrounded by a wreath, with what seems to be a military standard or a triangular symbol at the bottom.

Could you please help me with:

Identifying the type and period of this coin

Estimating its approximate market value if it is authentic

Any tips on verifying its authenticity

Thank you very much in advance!

 The first picture is a portrait of Tyche. 

https://en.wikipedia.org/wiki/Tyche 

 Pictures cropped 

 It is a coin from Ancient Greece: Ionia, Smyrna, AR Tetradrachm, 200-100 BC

Obverse - Head of Tyche to the right, wearing turreted crown. 

Reverse - ZMYP/NAIΩN, over a monogram, all within a laurel wreath. 

 Similar: N#433818