PIXE ANALYSIS OF JEWELS FROM AN ACHAEMENID TOMB (4TH-CENTURY-BC)

Ion beam analysis has seldom been applied to gemmology. The privileged location of the Laboratoire de recherche des musees de France, close to some of the most prestigious art collections, along with the implem entation of the AGLAE IBA facility, have allowed us to initiate severa l gemmological research programs since 1991. The latest of these deals with a series of Achaemenid jewels (IVth century BC) exhibited in the Louvre museum. The aim of the present research is three-fold: determi nation of the coloured materials inlayed in gold, composition of the g olden alloys and the inlay fixation technique. Analyses have been carr ied out by PIXE using an external proton beam under conditions set fro m test experiments on reference gemstones in order to optimise the exp erimental parameters. Quantitative chemical analysis of both major and trace elements has allowed us to distinguish between 15 types of fine or ornamental stones as well as man-made materials and to identify a peculiar cement technique. We will describe the analytical procedure i n detail, then present the main results obtained on coloured inlays an d cement and underline a potential drawback of the technique, i.e. a t ransient colour variation of the target under the impact of the beam, which needs further investigation.