Raman identification of materials used for jewellery and mosaics in Ifriqiya

Abstract Beads, rings and mosaic tessarae from Tunisia (Carthage and Utica, 1st centuries BC and AD , El Djem, 2nd–3rd centuries and Mahdia, 10th century) were analysed by Raman spectroscopy for non‐destructive differentiation of various types of glasses (most have Si‐ and Na/Ca‐rich compositions, some others are lead‐containing glass) and identification of synthetic or natural minerals (crystal or stone). The results are discussed in the light of chemical analyses. A green glass is coloured by a Cr‐based nanosized pigment and a red mosaic tesserae is obtained by a colloidal dispersion of gold (Cassius purple). Cassiterite (SnO 2 ) is used as an opacifier or fluxing agent. The examination of glass mosaic and jewellery microstructure shows that some pieces are made of sintered glass, i.e. using a paste technology. Copyright © 2003 John Wiley & Sons, Ltd.