You are looking at a tumbled piece of Cryolite, from Greenland. It has lovely Hematite or other form of Iron included. Those inclusions are lovely, brown colored with a bit of rainbows on it as well.
Energy wise this is a lovely stone. Cryolite has the ability to cleanse your energy from your highest source or highest chakra, all the way down. It purifies and protects. Because of its Iron like inclusions it gently grounds your energies, and therefore pulls the white Light from your highest Chakra, all the way down into the legs. Lovely.