What Is A Grey 1925 Wheat Cent?

Hard to tell, but you might add rub with mercury to the list. Thanks, Doug.

Oh I didn't know that your could do that with mercury. Just read a bit on amalgams, neat stuff. Will that effect the weight negatively or positively? Positively correct?

Almost certainly plated; possibly zinc, possibly nickel - I suspect the latter because zinc would probably have turned black by now, plus zinc doesn't turn green, while nickel does. It almost certainly won't be mercury, because mercury slowly evaporates over time, and the silvery colour of a mercury-washed copper coin fades back to copper again after a few decades.

As for "why", that's impossible to know unless you were there watching the plating happen. Maybe someone was trying to make a penny look like a dime (which is, of course, illegal). Maybe someone was just fooling around with chemicals. I personally own a "plated" Australian 2 cent piece, that looks silvery; it's zinc plated, and I only know this because my dad (a chemistry lecturer at university) made it as part of a chemistry demonstration.

Plating is the only logical answer, and the weight confirms it. Just a junk coin, sorry.

Coins rubbed with mercury will have a bright shiny mirror-like finish. How do I know? Friend's dad showed us how to make our steel LWCs look like new again back in the early '70s.

Are you suggesting they would look the same today? Thanks, Doug.

That is a significant amount of weight gain from the plating. Thanks for the follow-up on this coin. (just remember that curiosity killed the cat, but satisfaction brought it back)

Halo, never thought of this. All I know is mercury turned them a silver color. I guess we didn't keep them long enough to find out.