Dolomite is a calcium/magnesium carbonate mineral. It has a formula unit composition of CaMg(CO₃)₂. Dolomite has a trigonal crystal system with rhombohedral habit. In ideal dolomite, calcium and magnesium are separated into completed separate planes, quite unlike magnesian calcites in which Mg randomly substitutes for Ca. Most dolomite samples contain only a few percent of substitution of calcium for magnesium, and vice versa.

Dolomite is a calcium/magnesium carbonate mineral. It has a formula unit composition of CaMg(CO₃)₂. Dolomite has a trigonal crystal system with rhombohedral habit. In ideal dolomite, calcium and magnesium are separated into completed separate planes, quite unlike magnesian calcites. Most dolomite samples contain only a few percent of substitution of calcium for magnesium, and vice versa.

Distribution

Dolomite is a widely-occurring mineral and can be found in Spain, U.S., Canada, Switzerland, Austria and Hungary. Dolomitic limestone (dolostone) can be used for building stones and gravel, as well as a soil liming material when ground.

Although large deposits of dolomite are present in the geological record, there is little evidence of dolomite formation under current environmental conditions, including marine sediments and soils. Indeed, dolomite preparation under laboratory conditions at room temperatures and pressures remains one of the great challenges of mineralogy.

Miser, D.E., J.S. Swinnea and H. Steinfink. 1987. TEM observations and X-ray crystal-structure refinement of a twinned dolomite with a modulated microstructure. American Mineralogist. 72:188-193.