A heavy, reddish mineral form of mercuric sulfide, HgS, that is the principal ore of mercury. Cinnabar occurs in both crystallized and massive forms, has crystals that are six-sided prisms, and varies from perfectly opaque to almost transparent. Its specific gravity is 8.0 to 8.2. Hepatic cinnabar, so called from its liver-brown color, is a variety containing a little carbon.
Red mercuric sulfide used as a pigment under the name vermillion.