How can an eggshell from a chicken egg be naturally a mint green color?

I received a box of eggs from a friend whose neighbor raises chickens. One eggshell was mint green on the outside and inside. Why? Is there a variety of hen that lays this color?

How can an eggshell from a chicken egg be naturally a mint green color?
there are chickens that lay blue eggs


http://en.wikipedia.org/wiki/Araucana
Reply:No. This must have been something that was caused by a food source. Find out if the chickens are raised in cages or run free.
Reply:They come in a variety of colors. I have seen them green,tan, brown ,beige,a golden color and white . Maybe it's the diet of the chicken.
Reply:Araucana hen