What is a dolomite in geology ?

Dolomite : definition

Dolomite is a carbonate sedimentary rock close to limestone made up of more than 50% carbonates, at least half of which in the form of dolomite. A distinction is usually made between primary dolomites, resulting from the direct precipitation of large quantities of dolomite in coastal lagoons, and secondary dolomites, resulting from a replacement by metasomatosis of the initial calcite by dolomite (phenomenon of dolomitization).