https://doi.org/10.1140/epjp/s13360-025-05988-9
Regular Article
Micro-computed tomography and laser micro-ablation on altered pyrite in lapis lazuli to enhance provenance investigation: a new methodology and its application to archaeological cases
1
Dipartimento di Fisica, Università di Torino, Via Pietro Giuria 1, Turin, Italy
2
INFN Sezione di Torino, Via Pietro Giuria 1, Turin, Italy
3
University College London (UCL), Gower Street, WC1E 6BT, London, UK
4
Department of Anthropology, University of Wisconsin, 5240 Sewell Social Sciences Building, 1180 Observatory Drive, Madison, USA
5
Centre de Recherche et de Restauration des Musées de France, C2RMF, 14 quai François Mitterrand, Paris, France
6
UAR 3506 Lab-BC (CNRS, Ministère de la Culture, Chimie ParisTech), 14 quai François Mitterrand, Paris, France
Received:
27
September
2024
Accepted:
4
January
2025
Published online:
22
January
2025
This work presents an upgrade to the methodology adopted to investigate the provenance of the raw lapis lazuli material used in antiquity for carving precious artefacts. Samples from archaeological excavation contexts frequently display superficial degradation processes affecting the crystals of the mineral phases useful for provenance attribution (especially pyrite). To address this issue, an innovative workflow has been developed, centred on the application of X-ray micro-computed tomography (μ-CT) and micro-ablation treatments with a pulsed laser source prior to investigation with ion beam analysis (IBA). High-resolution μ-CT is employed to evaluate the alteration state of pyrite crystals within the entire volume of the lapis lazuli rock, and, if required, to identify the most suitable crystals on the surface for subsequent laser treatment. The micro-ablation procedure aims to create a small breach in the superficial altered layer (the irradiated areas are approximately 65 × 65 μm2), thereby exposing the preserved crystal beneath and allowing for the analysis of its trace element contents with IBA. The methodology of the workflow is presented, together with its first application to archaeological lapis lazuli material: three precious beads from the ancient Royal Cemetery of Ur (Mesopotamia, 3rd millennium BCE). The results are complemented by the application of a provenance protocol already validated that proved, for the first time using a micro-invasive analytical approach, a match between the Afghan quarry district and the raw material used to carve these beads.
Supplementary Information The online version contains supplementary material available at https://doi.org/10.1140/epjp/s13360-025-05988-9.
© The Author(s) 2025
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