This morning I suddenly remembered that I had put away two years ago a small selection of predecimal circulated coins mostly Elizabeth II and George VI. Anyway, I remember that when I put them away one of the coins (a rather worn 1893 penny) had a few spots of verdigris on it. Two years ago I was unaware of verdigris and it's effects. When I opened the jar this morning, I found that the coin that my 1893 penny was all virtually green, and about 50 other bronze coins had been coated in the crusty green slime! Just shows how easily it can spread to loads of coins from just a few minor spots.