Marble is a natural stone product and is known for it's veining patterns and variation in color. Marble has both a commercial and scientific definition. Scientific marble was once limestone that achieved metamorphosis from high temperatures and intense pressures within the earth. This altered its crystalline structure and introduced other minerals that produced the valuable colors and veining. Commercial marble is defined as any stone capable of being polished (with the exception of granite). This includes travertine, onyx, serpentine and limestone.