If you have a gun powder scale, the balance beam type, you can use it to find the specific gravity of the coin; it's pretty easy, just look on YouTube for a 'how to' and once you have a hard number, look up the specific gravity of various metals for a match close enough to get you started.
An acid test, such as a pawn shop or other gold buyer will perform will damage the finish of the coin, so be aware.
Lastly, the First Thing you should do is take a strong magnet, with a thickness of towel or wash cloth between the coin and the magnet, and see if its ferrous metal like iron or steel or tin, etc., to see if it's worth the bother before going any further.
Good Luck.