Proposal of a new in-situ, non-invasive tool for characterizing building stones in archaeological contexts – the Pyrgi case study, Italy

When dealing with archaeological finds, analytical strategies that allows to obtain as more information as possible, without the need of sampling, are always desirable. In particular, if the sample to be analysed belongs to an architectural structure, such as a foundation or a building wall that can hardly be sampled or transported, realising a suitable analytical approach becomes challenging. To try to solve this type of problem, a non-invasive and non-destructive procedure has been proposed. Indeed, the combination of portable digital microscopy (Previti et al., 2024) and External Reflectance Fourier-Transform Infrared Spectroscopy (ER-FTIR)(Brunello et al., 2019) can provide adequate information to preliminarily describe and grouping lithic samples as part of building and structures directly on-site. Lithic samples located inside the archaeological site of Pyrgi (Italy) (Baglione et al., 2015) were used as case study: the multi-analytical approach performed in-situ, combining digital images and spectroscopic data, enabled the sorting of the selected samples into distinct groups based on shared characteristics, allowing for a more detailed comparison, and understanding of their properties. This type of approach allows for a preliminary characterisation of the investigated area, avoiding unnecessary sampling and giving the possibility of concentrating only on particularly interesting or representative samples of each group. In fact, thanks to this approach the number of samples subjected to in-depth destructive analyses was smaller than in a traditional scientific analysis campaign. Some peculiar samples were selected for additional investigation on their mineralogical composition and chemical structure, performing Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (FTIR ATR), X-ray powder diffraction (XRPD) and petrographic optical microscopy. Acknowledgements: this work is part of the EDIFICIA Project, winner of the Sapienza BE-FOR-ERC 2024 grant, CUP B83C25001000006 Baglione, M.P. et al. (2015) - Pyrgi. A Sanctuary in the middle of the Mediterranean Sea. In: Kistler E., Ohlinger B., Mohr M., Hoernes M. (eds.), Sanctuaries and the power of consumption. Networking and formation of the elites in the archaic Western Mediterranean world. Proccedings of the International Conference in Innsbruck, 20th-23rd March 2012.(PHILIPPIKA WIESB.), pp. 221–237. Brunello, V. et al. (2019) - Non-invasive FTIR study of mortar model samples: comparison among innovative and traditional techniques. The European Physical Journal Plus, 134(6), 270. https://doi.org/10.1140/epjp/i2019-12667-1. Previti, G., Luci, B. & Lemorini, C. (2024) - Micro-photogrammetry and traceology: new on-site documentation approaches using portable digital microscopes, Journal of Archaeological Science, 168,106004. https://doi.org/10.1016/j.jas.2024.106004.