Similar to limestones, dolomite rocks are sometimes referred to as marble even if they have not undergone metamorphism, which is considered an essential occurrence for the formation of true marbles in a geological sense of the word. The reason for this seemingly erratic usage of terminology is that dolomite is a predominantly carbonate rock that takes a good shine when polished. This fact, along with its hardness and occurrence in a variety of colors and beautiful variegated forms, enables the rock to be readily utilized as an ornamental stone, as is true, metamorphosed marble. An example of dolomite used in this manner is the popular Tennessee marble, a coarsely crystalline form of the rock that has not endured metamorphism.