Probably you cracked it while opening it..... lol. Haven't heard of a coin problem like this before. I had an 1874 $3 gold piece coin
http://www.meritgold.com/product-de...3-gold-piece which I
inherited from my grandpa. It was in a beautiful matte finish, but accidently lost it one day. Since then I don't collect collectible coins, only browse about them and invest in bullions coins mostly from the U.S. Mint. Right now I'm eyeing the ‘America the beautiful series'
http://www.usmint.gov/mint_programs/atb/