Although both are stones and quarried from the earth, granite and marble (and marbleâ€™s relatives â€“ limestone, onyx and travertine) are very different from each other. Granite is formed deep in the earthâ€™s mantle at extremely high temperatures. It is a very hard, resistant stone made of crystallized minerals. The marble family start out as sediment at the bottom of bodies of water. After millions of years it becomes stone.