Cathodoluminescence Spectroscopy of Quartz Grains as a Tool for Ceramic Provenance

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This paper examines the possibility of differentiating between two ceramic types by using cathodoluminescence (CL) investigation. Ceramics are from two sites (Auvernier-la-Saunerie and Charavines) of the Neolithic civilization of Saône-Rhône (2900–2400 bc). A standard site also was built with a low-calcite clay and a sandstone from south Germany. The method consists of comparing the CL spectra of quartz grains in ceramics. CL can be defined as a visible and near visible light (from 1·4 eV to 4·2 eV) emitted upon the interaction between an electron beam and matter. For the analysis a scanning electron microscope coupled with an optical detection system was used. Three to six quartz grains were analysed from each sample. Conditions were constant for each acquisition. All the CL spectra of quartz exhibited two components, a blue component centred at 2·75±0·04 eV, and an orange–red centred at 1·93±0·03 eV. To compare all the spectra the ratio (R) between relative intensities of blue and red bands was calculated. The results demonstrated that it is possible to define several types of CL for quartz grains. Using this property, a mean and standard deviation of ratio R was calculated for each ceramic and plotted on a two-dimensional diagram. Samples from Charavines and the standard group were clearly separated. CL spectra of the ceramics from Auvernier were similar to Charavines but did not give clear differentiation. The use of the CL signal from other minerals, such as calcite, gave a better distinction for these ceramics.