4 tubes round 1966 50c (25 in each) anyone do Brisbane f2f? $1325 none bent/damaged, but some toning. Photo shows 1 tube.
Far as I know it's just a reaction with what's in the air that happens over a long period of time most likely with the copper in the coin turning it green or black. Can be cleaned if you like them nice and shiny . Only had the tubes 6 months max and coins were like that long before.