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A sedimentary rock type, usually formed by the dolomitization of limestones, and commonly occurring interbedded with them. Most limestones contain some magnesium carbonate and strictly the term ‘dolomite’ refers to rocks containing 90% or more of the mineral dolomite (see 1). Dolomite that has formed soon after deposition tends to be fine-grained and to have preserved the original sedimentary structures, whereas recrystallization in late-diagenetic dolomites produces a coarser-grained rock, a loss of sedimentary structures, and an increases in porosity. — A Dictionary of Geology and Earth Sciences (4 ed.), Oxford University Press