As the favorite medium for Greek and Roman sculptors and architects, marble has become a cultural symbol of tradition and refined taste. Its extremely varied and colorful patterns make it a favorite decorative material. Usually, marble contains other minerals, including quartz, graphite, pyrite, and iron oxides. These minerals can give marble a pink, brown, gray, green, or variegated coloration. While true marble forms from limestone, there is also dolomitic marble, which forms when dolomite undergoes metamorphosis. The statue of Lincoln in the Lincoln Memorial is made of white marble from Georgia, while the floor is pink Tennessee marble, and the exterior facade is marble from Colorado.