Infrared reflectance spectroscopy as an analytical technique for the study of residues on stone tools : potential and challenges

摘要

FTIR (Fourier transform infrared) spectroscopy is a non-destructive analytical method that has been usedsuccessfully to analyse both inorganic and organic archaeological material. Using a microscope attachmenthas the additional benefit of analysing very small spots (diameter 100 mm) directly on an artefactwithout sample preparation or destruction. It is therefore a suitable method to study residues on prehistoricstone tools. However, using a microscope without an ATR (attenuated total reflection) microscopeobjective, results in a combination of reflection and transmission/absorbance FTIR spectra, which isnot always as easy to interpret as directly measured transmission/absorbance spectra. In order toimprove the interpretation of spectra recorded on archaeological samples, the method was tested withreplicated Middle Stone Age stone points used during hunting and butchery experiments on parts of ablue wildebeest (Connochaetes taurinus) published in 2004 (Lombard et al., 2004). In this case, theresidues on the tools were known and post-depositional contamination was eliminated. Additionalsamples of the organic materials, and the minerals from which the tools were made were also available.Therefore, we could assess the viability of FTIR reflectance spectra for distinguishing between bone, fatand protein residues.