Pigment made from the mineral cinnabar, composed of mercuric sulfide. Cinnabar was finely ground for use as an artist pigment since antiquity. Red mercuric sulfide has been made synthetically since at least the 8th century in Europe and possibly earlier in China. Synthetic mercuric sulfide is called vermilion, favored over ground cinnabar as a red pigment because cinnabar, when exposed to ultraviolet light, darkens from its normal red crystalline form to a black isomorph, resulting in splotchy discolorations.