Identification and diagnostic study of Neolithic beads from Kalyvia, Attica, applying Raman spectroscopy

E. Kougemitrou, G. Moraitou, S. Raftopoulou, G. Chela & K. Polykreti In E. Photos-Jones, Y. Bassiakos, E. Filippaki, A. Hein, I. Karatasios, V. Kilikoglou & E. Kouloumpi (eds), 2016. Proceedings of the 6th Symposium of the Hellenic Society for Archaeometry (Bar International Series 2780), Oxford: 33-39.

The international literature is limited on the subject of the study of corrosion of ancient mollusc shells that have been preserved in taphonomic conditions. Physicochemical analysis of samples has been published while the corrosion processes are considered to be identical to those of the constituents of shells, ignoring their elaborate structure. Five out of eleven beads from a Neolithic context were found at an excavation of a cave at Kalyvia in Attica, Greece. They were brought to the conservation laboratory of the 2nd Ephorate of Antiquities to be identified and conserved. Their corrosion pattern resembled that of glass. Although glass was not manufactured in Neolithic times and the beads were most probably made of shell it was then decided that they be analyzed by the non-destructive method of Raman spectroscopy. The results of the analysis in combination with macroscopic and microscopic observations indicate that they are mollusc shells (gastropods or bivalves) which are known to dominate the Neolithic adornment either worked or unworked. In this study, given the limited literature on this subject, an overview is attempted of the problem that arises, from the composition and structure of the primary material in conjunction with possible corrosion processes in the taphonomic conditions to a number of possible explanations for structural/physico-chemical composition between ancient and modern shells. However, the organic matter predominates quantitatively compared to the inorganic crystalline components (calcite/aragonite). This does not agree with modem mollusc shells analyzed for comparison.