It's called Environmental Toning Damage to the Reverse. Not a Mint Error. But since you didn't create this thread over at the Error Coins forum I will tell you the value.. Right @lordmarcovan ? Worth? 25 Cents
Yep. Just dark toning from environmental factors. Spent some time exposed to the elements. Not worth any premium. Kinda neat looking, though. It's only worth a quarter, but the dark toning is not as ugly as I've seen. I almost like it. My detector finds of clad quarters like this are usually brown, from the ground minerals.
