Neutron Activation Analysis of Ancient Amerindian Ceramics and Clays

Abstract

In the present work we are interested in the neutron activation analysis of the prehistoric Quebec Amerindian ceramics and the clay belonging to the regions where these ceramic objects were discovered. All analyses have been done using the SLOWPOKE-2 (Safe Low Power Critical Experimental) nuclear reactor of the Ecole Polytechnique of Montreal. The purpose of our research is to study the variation of the chemical composition of clay belonging to different regions of the Saint Lawrence Lowlands. From their chemical composition we can deduce if prehistoric ceramics were made with local "in situ" clay or if they were imported Knowing the composition variability of clay belonging to different regions it may be possible to classify the ceramics according to their probable region of manufacture. For every sample of ceramic and clay, we have determined the concentration of twenty-five chemical elements: Sm, Al, Rb, Na, Yb, Hf, Fe, Sc, Tb, Th, Lu, Eu, V, Dy, Cs,Mg, Ti, K, Mn, Ba, Ta, U, Ce, La. From statistical tests we have classified these chemical elements according to their ability to separate clays from different regions . We obtained die best separation using sixteen chemical elements (Sm, Al, ..., Me). From the results of the analysis of dl the clay samples we have elaborated a scientific method based on a mathematical algorithm. This method has allowed us to group the clay samples of similar chemical composition to create associations, to which we have associated the ceramic samples studied. This correspondence was achieved by calculating proximity values between the ceramic samples and the different associations. The implantation of this method has allowed us to classify the ceramics studied by zone and by region. Thus, for each sample of ceramic we indicated its zone and the probable source region(s) of the clay which was used for its manufacture.