@PBJ1523, first welcome to CCF. Second, I agree that some sort of environmental exposure is the most likely reason for the color on this coin. It looks kinda neat and so may be worth adding to your collection for that reason, but otherwise can be spent.
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz