Characterization of azurite and lazurite based pigments by laser induced breakdown spectroscopy and micro-Raman spectroscopy

The most commonly used blue pigments in medieval manuscripts are azurite and lapis-lazuli. The first one is a copper-based pigment; the coloring compound of the latter is lazurite, a sodium silico-aluminate in a sulfur matrix. Knowledge of the chemical composition of the materials is essential for the study of illuminated manuscripts. In this paper, micro-Raman and LIBS have been used for the study of azurite and lapis-lazuli, as well as different mixtures of these pigments applied to parchment to simulate an illuminated manuscript. The results of our work show the importance of using more than one technique for a good comprehension of a manuscript. In particular, the opportunity of combining elemental information (obtained from laser induced breakdown spectroscopy) and vibrational spectroscopy information (obtained from Raman) will be fully exploited. (C) 2001 Elsevier Science B.V. All rights reserved.