Hello, I don't consider myself a very good grader (yet...) and I want some opinions on my nickel. My guess is it's XF-45.
All over . . . it exhibits micro-porosity throughout, likely from having spent time in acidic surroundings.
Unfortunately... everywhere. When you see a black nickel like this, the immediate and first response is environmental damage. Look at the roughness of the fields. That micro-porosity is classic environmental damage. In terms of level of wear, I agree that it has EF details.
Maybe? Surface contamination may still be present. Given what I'm seeing, it is unlikely, but it seems to have been in an acidic environment. The crust on the surface may not be stable, and may be continuing to damage the coin. I can't rule that out based on these images.
My point is that the coin appears to have uniformly corroded over its entire surface, which implies complete immersion. Localized exposure would have produced spot corrosion instead. If there is any remaining reactive potential, it should be short-lived.
When a copper-nickel corrodes, it turns gray or more often black. Sometimes you will see some green spots because of the copper in the coin. Remember, these coins have more copper in them than nickel. When you see black toning on a copper-nickel cent (Flying Eagle, Indian 1859 to ‘64, Nickel Three Cent Piece or five cent nickel, it’s not good, regardless of the sharpness.
