Quote: As above, they didn't leave the mint like that.
Actually, they did. Modern proof, specimen, and Uncirculated Loon coins left the mint with a coating of lacquer on them. I think what we are seeing is the degradation of the lacquer coating on these coins, within the sealed flips shown here.
"Discovery follows discovery, each both raising and answering questions, each ending a long search, and each providing the new instruments for a new search." -- J. Robert Oppenheimer