Sulfur in Artwork: Lapis Lazuli and Ultramarine Pigments

Abstract

The S-contg. aluminosilicate mineral lazurite, called lapis lazuli, prized as a valuable semiprecious gem since the classical era, and as the raw material for the prodn. of the brilliant blue pigment ultramarine in the Middle Ages, represents 1 of the most fascinating objects of structural inorg. chem. After a short outline of the history of the lapis lazuli and the artificial ultramarines, some of the pathways are described which led to the solns. of the problem of the constitution of these substances. Their chromophores are small S mols., S3 (yellow), S4 (red), and, preferably, radical ions S2- (yellow), S3- (blue), S4- (red), which are imbedded in the cavities of the sodalite lattice.