SURFACE INVESTIGATIONS OF ARCHAEOLOGICAL GLASSES BY SECONDARY ION MASS SPECTROMETRY

One of the aims of the project “PARNASO – Dallo Scavo al Museo” was the development of analytical procedures for the physical chemical characterization of archaeological glasses and bronzes. The surface investigation of historical objects can be useful both to date the artefacts and to understand their manufacture techniques. The study of the decay of specific elements, in fact, can make it possible to date archaeological glasses; moreover the use of specific raw materials, available in a certain area, allows specific glass compositions to be linked to regional manufacture sites. Secondary Ion Mass Spectrometry (SIMS) has proved to be a suitable analytical technique to highlight some of the principal characteristics of the ancient glass manufacture, of the raw materials and of the recipes; in fact, it has high sensitivity to trace elements and provides spatially resolved information in the micron and sub-micron ranges. Moreover, SIMS provides compositional analyses in a short time and needs only small amounts of material, as required in the archaeological field. In this work we present a new analytical approach to characterize archaeological artefacts, focusing our attention on SIMS analysis of glass objects. Both synthetic glass samples and ancient objects, found in the Altino archaeological site (Venice, Italy) were studied. A complete methodology has been developed: all the problems relating to sample preparation, analytical artefacts, accuracy and reproducibility have been solved. All the results obtained are shown and discussed; SIMS profiles were cross related to complementary techniques results like XPS, AFM and ToF-SIMS.