Painting the Ancient World
Crystallochemical Characterisation of Pigments and Minerals in Ancient Written Artefacts
2022–2025
RFA19
The main objective of this project is to determine non-destructively the crystallochemical characteristics of the mineral phases comprising cultural-heritage objects, as well as of pigments that have been used for their colouration. For this purpose, the chemical and structural properties of colour and weathering-related products on rock-based inscriptions and their writing supports, as well as on other objects from two different localities of Hellenistic and Imperial Greece and Asia Minor are going to be analysed comprehensively. A multianalytical approach of non-destructive analytical techniques such as Raman spectroscopy, Fourier-transform infrared (FTIR) reflection spectroscopy, X-ray fluorescence (XRF) reflection, and near-infrared spectroscopy (NIR), is needed to gain such information. In particular, the application of Raman spectroscopy will be extremely important, since it has the ability to detect differences in the weathering-related products between inscribed and non-inscribed areas of the same specimen, as has already been proven for the crack-enhanced weathering in engraved marble-based written artefacts. In addition, the potential of micro-spatially offset Raman spectroscopy to study non-invasively the chemical and structural composition of subsurface layers in painted and/or restored rock-based written artefacts will be explored to elucidate the artefact conservational history and provenance.
The second part of this project will be dedicated to the development of quantitative relationships between the crystal chemistry and Raman scattering selected subgroups of layered silicates, present in cultural heritage objects, by following the already established methodology for biotites. The non-destructive determination by Raman spectroscopy of the mineral-phase and corresponding crystallochemical composition of cylinder seals, dated between 3200 and 400 BCE, will highlight the application of this methodological approach (e.g.: Figure 1).
Overall, these features can reveal peculiar characteristics of societies, and therefore they are key-factors in studying coloured inscriptions, their rock-based writing supports, as well as the origin and conservational history of a coloured object. Moreover, knowledge of chemistry and the structure of mineral groups that are present in common cultural heritage objects may advance provenance studies.
People
Principal Investigator: Stylianos Aspiotis