HgS. A soft, dense, red, native ore composed of mercuric sulphide. Cinnabar is widely distributed around the world and is most often found in veins near volcanic rocks or hot springs. It has been mined from the Spanish cliffs near Almadén for over 2000 years. Other deposits are found in Italy (Iudrio), Germany, Austria, Yugoslavia, China (Hunan, Kweichow), Turkestan, Mexico, Peru (Huancavelica) and the United States (Texas, California). Cinnabar was finely ground for use as an artist pigment since antiquity. Red mercuric sulphide has been made synthetically since at least the 8th century in Europe and possibly earlier in China. Synthetic mercuric sulphide is called vermilion. Due to impurities, vermilion was favoured over ground cinnabar as a red pigment. When exposed to ultraviolet light, mercuric sulphide darkens as a portion changes from its normal red crystalline form to a black isomorph. This can result in splotchy discolorations. It is listed among the pigments and dyes used for colouring stucco marble in the seventeenth and eighteenth century. Synonyms: vermilion (synthetic pigment); Chinese vermilion; English vermilion; Pigment Red 106; CI 77766; red mercuric sulphide; red sulphuretted oxide of mercury; liver ore; Zinnober (Ger.); cinabrio (Sp.); cinabre (Fr.); cinabro (It.); shinsha (Jap.); tan-sha (Chin.). Wittenburg (1999); Museum of Fine Arts, Boston (2000). [J. Cassar, R. de Angelis]