It was probably moldy, and if not, then it was probably moldy. But I would need pictures to tell if it were either moldy or moldy.
Could be toned from a variety of environmental factors. Could be painted green. Could be radioactive. Could be it's not a dime at all, but in fact a 10-povlar piece from the Glorg Federation on Planet Znutar, which is one of the few extraterrestrial entities to use coins. (Their 10-povlar pieces are green, you see, while the 25-povlars are more of a bluish color.)
It can turn green with verdigris as it is mostly copper. I have found them under car seats that are green.
Someone who drank green beer pee'd on it. ask yourself a question. If the DIME is made out of metal, then how does it turn green? modern dimes are 91.67% Copper - 8.33% Nickel. look up what happens to both of those metals over time when exposed to the environment (like verdigris) . Also, who put the dime in the drawer; what did they do to the dime from the time it was minted (and they rec'd it directly from the mint right ?) to the time they put it in the drawer. Of course, that's just environmental damage. If it's moldy from something, that is something else. If someone exposed it to something else, then that's another damage thing. If your lights have a green hue ... well ... maybe post a few pictures of the coin front and back to help avoid all the speculation ?
Welcome to CT James. Keep looking. If you are a cashier, ask management if you can exchange coins from your pocket or when you cash out your drawer. Good luck.
