Potential role of LIPS elemental depth profiling in authentication studies of unglazed earthenware artifacts

We focused on the behaviour of elemental distributions in unglazed earthenware artifacts. The potential role of the elemental depth profiles, as measured using a portable laser induced plasma spectroscopy (LIPS) device, in discriminating between genuine unearthed archaeological findings and modern counterfeits was investigated. Measurements were carried out on a set of ancient unglazed earthenware samples from archaeological excavation and on some corresponding modern artifacts. The analyses pointed out that the elements exhibiting the most significant and repeatable modulations were iron and calcium. A systematic depletion of the former was observed in all the samples analysed, without any possibility of discrimination, whereas calcium had different behaviours. A recurrent presence of high-amplitude, broad, and structured calcium content peaks in proximity of the surface of genuine unearthed samples was measured, a feature that was not observed for modern artifacts. This result provides the first evidence of the possible use of calcium depth distribution measured using LIPS analysis as a marker in authentication studies of unglazed earthenware artifacts.