Dolomite \Dol"o*mite\, n. [After the French geologist Dolomieu.]

(Geol. & Min.) A mineral consisting of the carbonate of lime and magnesia in varying proportions. It occurs in distinct crystals, and in extensive beds as a compact limestone, often crystalline granular, either white or clouded. It includes much of the common white marble. Also called bitter spar.

Source: Webster's Revised Unabridged Dictionary (1913)