Black copper maran?!?!

[rural mouse]

If she shows copper in later moults, then it's possible. Her tail isn't right for a cochin. Black Langshan is another feather-footed black breed. I don't know enough about those to say definitively, but would be worth looking up. Shell color will help identify her breed. Skin color (check the bottoms of her feet) may also help. Marans are supposed to have white skin.