Abstract:
FTIR (Fourier transform infrared) spectroscopy is a non-destructive analytical method that has been used
successfully to analyse both inorganic and organic archaeological material. Using a microscope attachment
has the additional benefit of analysing very small spots (diameter 100 mm) directly on an artefact
without sample preparation or destruction. It is therefore a suitable method to study residues on prehistoric
stone tools. However, using a microscope without an ATR (attenuated total reflection) microscope
objective, results in a combination of reflection and transmission/absorbance FTIR spectra, which is
not always as easy to interpret as directly measured transmission/absorbance spectra. In order to
improve the interpretation of spectra recorded on archaeological samples, the method was tested with
replicated Middle Stone Age stone points used during hunting and butchery experiments on parts of a
blue wildebeest (Connochaetes taurinus) published in 2004 (Lombard et al., 2004). In this case, the
residues on the tools were known and post-depositional contamination was eliminated. Additional
samples 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, fat
and protein residues.
