There's a very rare stone that's tan and contains a natural cross-like formation...does anyone know the name?

I've read about it somewhere, and the image stands pretty clearly in my mind; but I have no idea what the name is. They aren't Moqui marbles, but I seem to remember something being mentioned about aborigines, talismans and Australia. Some claim that the stones are exceptional for healing (for those that follow stone healing, metaphysics, etc), and that their rarity makes coming across one an extremely good omen.