I was nickel coin roll hunting and came a cross a lot of toned and dirty coins. Does anyone know what causes this?
They were in a toilet, urinal, fountain, pond, dirt, or something. They aren't toned. They are environmentally damaged.
Getting wet with something -- roadside/parking-lot water, spilled soft drink, sweat -- and then sitting long enough to corrode. Edit: or, as @physics-fan3.14, other body products. Welcome to CoinTalk! Now, go wash your hands.
Here are a few I got today. That quarter is gnarly. And you can see one of the nickels and dimes are as well.
Welcome to CT Chris. That does seem like a lot of dirty coins. How many rolls did you search to come up with them? Unless you can find any with errors, I'd re-roll them and send them back, and as @-jeffB said, "Now, go wash your hands." LOL