I found this dime in my change, what do you guys think it's worth? http://s1144.photobucket.com/albums/o481/stevjagi1/?action=view¤t=SAM_1752.jpg http://s1144.photobucket.com/albums/o481/stevjagi1/?action=view¤t=SAM_1754.jpg&newest=1
Cool!! Looks like most of the clad layer came off after the coin was struck. That one is a keeper. Good job!
Sulfuric Acid would only eat the clad layer. Notice the same loss of detail in the copper layer that the dime has.
This is so. It (Sulfuric Acid) attacks reactive metals (metals at positions above copper in the reactivity series) such as iron, aluminium, zinc, manganese, magnesium and nickel. http://en.wikipedia.org/wiki/Sulfuric_acid#Reactions_with_metals_and_strong_oxidizing_property
Problem with your theory is, you couldn't get the dime to look like the OP's with acid as you wouldn't be able to control the acid in such away as to leave a clean breaking line like what's on this dime. Looks like exactly what the others have stated, it occurred after the coin was struck and is a keeper with a value more than face.
I don't know what happened to this dime, but you can control the acid with tape. I've done it before when frosting glass. One big difference though is smooth surface vs textured surface. I'm not sure one would be able to get a good clean line along the uneven surface of the dime. What if it was suspended in a more fluid acid? I think you'd be able to tell if you examined the coin closely. If it was taped, there would probably be some undercutting along the line where the acid ate up under the area that was protected by the tape. If it was suspended, it would probably taper the other way around due to evaporation of the acid over the time it took to eat away the cladding. Either way, interesting coin and it's fun to try and figure out what happened.
Thanks for all the replies everyone. I'm going to take the dime to a chemist and my school to see what he thinks about the sulfuic acid idea. It seems if someone were using acid that the front of the dime would also have lost the clad layer. Until then it remains a mystery! Cheers