Dolomite is slightly harder than limestone. Dolomite has a Mohs hardness of 3.5 to 4, and limestone (composed of the mineral calcite) has a hardness of 3.

Dolomite is slightly less soluble in dilute hydrochloric acid. Calcite will effervesce vigorously in contact with cold, dilute (5%) hydrochloric acid, while dolomite produces a very weak effervescence.

These differences are often not significant enough to make a positive identification in the field. Distinguishing the rocks in the field is further complicated by a compositional continuum that ranges from limestone to dolomitic limestone to dolomite. A chemical analysis that determines the relative abundances of calcium and magnesium is needed to accurately name the rocks.