Dolomite. Dolomite is the name of a sedimentary carbonate rock and a mineral, both composed of calcium magnesium carbonate Ca Mg ( C O 3) 2. As a mineral, it is found in crystals. Dolomite rock (or 'dolostone') is mostly made of the mineral dolomite. Limestone that is partially replaced by dolomite is referred to as dolomitic limestone.
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