Travertine and Limestone are more porous than most stones and are relatively soft, compared to granite. Travertine is usually characterized by a pitted surface which can be filled or left open. Limestone is generally cream or white in color but if it contains some iron oxide, colors can vary from brown, yellow or red. If limestone contains carbon it can be gray, black or even blue in color. If not properly cared for, their surfaces can look dark from dirt and soil accumulation. Both types of stone should be sealed.