Is it possible to have a black golden retriever ?

My family adopted a dog that was portrayed to be a black "Newfoundland". When we first got her, I thought she was a golden retriever, but black of course. The breeder was unknown since we got her from a pet store. She is very happy and healthy, but I was just wondering if it is possible to have a black golden retriever. If you compared a golden to my dog, you would find no differences other than that my dog is black.