ANALYSIS OF ANCIENT METAL COIN USING DIFFERENT EXPERIMENTAL TECHNIQUES AND METHODS OF MULTIVARIATE ANALYSIS

Different spectroscopic techniques, in combination with suitable statistical methods of multivariate analysis, can be applied in explorations investigation in various fields, including industry, environment, agriculture, medicine and cultural heritage, for example. For well-known reasons, in analyses of cultural heritage artifacts only full or nearly non-destructive experimental methods must be used. In this paper, we have chosen the ancient metal coin, found on the territory of the present Republic of Croatia and made during the reign of little known Illyrian king Ballaios. To evaluate its value and other characteristics we have used x-ray fluorescence and micro-Raman spectroscopy as two non-destructive experimental techniques, as well as micro destructive method of laser ablation, called laser induced breakdown spectroscopy. The spectroscopic data, obtained using these methods, consist of several thousand variables, mostly auto correlated. For the qualitative and quantitative interpretation of such data we have applied two methods of multivariate analysis. The principal component analysis is used for reducing the dimensionality and interpretation or classification of data set, while the partial least square analysis is used to create a calibration model to be used for analyzing unknown samples.