Marble is a metamorphic rock formed from the recrystallization of limestone under intense pressure and high temperatures within the earth. During this process, other minerals are introduced into the structure, which produce beautiful colors and veining which characterize marble. Marble countertop colors vary from white to black, being sometimes yellow, red and green, and frequently beautifully veined or clouded. Marble is scratch- and stain-prone, as it is not as hard as a granite surface. It is not preferred in the kitchen, but works well in bathrooms, on hearths, and in some furniture applications.