Type of limestone, the carbonate fraction of which is dominated by the mineral dolomite, calcium magnesium carbonate CaMg(CO 3 ) 2 .
The carbonate mineral dolomite occurs in marbles, talc schists, and other magnesium-rich metamorphic rocks. It occurs in hydrothermal veins, in cavities in carbonate rocks, and less often in various sedimentary rocks as a cement. It is most common as a rock-forming mineral in carbonate rocks.