Also show the reverse and edge. Most Nickels that are fund in circulation and are darker in color are just Environmental Damage.
While this is not in my wheelhouse of knowledge I'm still going with just ED even without seeing the rim. Only the recessed areas show darkening while all raised effects are lighter toned from normal wear & tear. JMHO of course so don't let that stop you from searching. I too was a newbie at one point and in a lot of areas I still am.
I did like the color on this coin. And the date is correct. (58 and 59) However, the rim is the same color as the coin. And I believe that with improperly annealed planchets, that is not the case.