A massive, compact limestone; a variety of calcite, capable
   of being polished and used for architectural and ornamental purposes.
   The color varies from white to black, being sometimes yellow, red, and
   green, and frequently beautifully veined or clouded. The name is also
   given to other rocks of like use and appearance, as serpentine or verd
   antique marble, and less properly to polished porphyry, granite, etc.