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Stone University

The Marble Group

Like granite, the term "marble" has both a geological and commercial definition. Geologically, marble is a "metamorphic rock consisting of fine to coarse-grained recrystallized calcite and/or dolomite." Commercially, the term marble is used to describe any crystallized carbonate rock including true marble and certain limestones (orthomarble) that is capable of taking a polish. Travertine and serpentine, while not true marbles, are usually included in the commercial definition of marble. A geologic marble of pure calcite or dolomite would be white. Marbles are available in a vast array of colors, and the variety of colors is the result of impurities found in the marbles, such as iron oxides, carbonaceous minerals, mica, chlorite or silicate.