MARBLE: Metamorphic rock containing over 50% of carbonate calcites and/or dolomites and/or aragonites. It is indicated as pure if the carbonates exceed 95% and impure in all other cases. Any compact rock which is strong and can be polished, whose hardness exceeds the values of 4 / 4.5 on the Mohs scale. Commercially, the term includes, in addition to marbles in the strictest sense, calcareous stone, alabasters, cipolin marble, dolostones, onyx, serpentinites, etc… Also Commercial marble.