Split plating. When they punched the die with the mint mark punch, the punch sometimes makes a fin on the bottom of the mint mark. After many coins are struck this fin flattens, but the ones struck before that happen have the plating split. The zinc deteriorates and it goes through this:
http://imgs.inkfrog.com/pix/coop49/Rise_Fall_Fell_Off.jpg
Many zincolns look like that pre 1990.
suprajason
05-09-2013, 02:01 AM
those are cool lookin esp the second one. so.. the same thing on the back? theres no trace of the bottom of the u
Yes. Even pin holes will make the same affect. Sometimes you find that sitting in water can also make a small split spread.