Granite is created at extraordinarily high temperatures deep within the earth's mantle. Limestone, travertine, marble, and onyx are all members of the marble family, which begin as sediment — animal skeletons and shells, plant matter, and silt – at the bottom of bodies of water. This solidifies into stone over millions of years. In comparison to granite or marble, quartz, as a man-made object, has a homogeneous appearance in most circumstances.