Sometimes when I cook chicken breasts in my iron skillet, these dark green spots appear. To me they look like a nasty mold, but I'm sure thats not what they are because they appear within an hour or two after cooking, and they never spread. I wonder if its some kind of reaction with the iron pan. I tried a different iron pan and got the same thing. They are cooked without oil. The green spots are only on the outside of the chicken - I've been slicing that part off and eating the rest of the chicken, and it tastes normal.
Cross-posted in Nutrition.