Dolomite is an anhydrous carbonate mineral, its name is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite (see Dolomite (rock)). An alternative name sometimes used for the dolomitic rock type is dolostone.

Dolomite is used as an ornamental stone, a concrete aggregate, and a source of magnesium oxide, as well as in the Pidgeon process for the production of magnesium. It is an important petroleum reservoir rock, and serves as the host rock for large strata-bound Mississippi Valley-Type (MVT) ore deposits of base metals such as lead, zinc, and copper. Where calcite limestone is uncommon or too costly, dolomite is sometimes used in its place as a flux for the smelting of iron and steel. Large quantities of processed dolomite are used in the production of float glass.

In horticulture, dolomite and dolomitic limestone are added to soils and soilless potting mixes as a pH buffer and as a magnesium source. Pastures can be limed with dolomitic lime to raise their pH and where there is a magnesium deficiency.

Dolomite is also used as the substrate in marine (saltwater) aquariums to help buffer changes in the pH of the water.

The main difference between dolomite and dolostone is that dolomite is a mineral, while dolostone is a sedimentary rock that's primarily made of dolomite. While not as widespread as limestone, dolostone makes up 2% of the earths crust making it very common and usually found in older formations.