An innovative electron paramagnetic resonance and statistical analysis approach to investigate the geographical origin of multi-layered samples from a Renaissance painting

• Published in: Microchemical journal 2022-06, Vol.177, p.107219, Article 107219
• Main Authors: Romanelli, Maurizio, Buccianti, Antonella, Di Benedetto, Francesco, Bellucci, Lorenzo, Cemicky, Stefan
• Format: Article
• Language: English
• Subjects: Calcite; EPR spectroscopy; Provenance; Renaissance painting; Statistical analysis
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2022.107219

[Display omitted] •A novel method based on EPR spectroscopy and statistical analysis is presented.•Samples consist of CaCO3 layer in a highly complex, multi-layered material.•Identification of the mineralogical nature of a carbonate layer is obtained.•Clues to the assessment of the geographical provenance of CaCO3 were provided.•This microinvasive method is reliable for future applications in cultural heritage studies. The present study aims at unravelling whether an innovative, integrated method based on electron paramagnetic resonance (EPR) spectroscopy and statistical analysis could shed light on the mineralogical attribution of calcium carbonate, CaCO3, microcrystalline powders found in an unusual preparation layer of a Renaissance painting on wood. Moreover, the undertaken investigation was performed to assess, if possible, the geographical provenance of the same carbonate powders. A specifically designed procedure was operated based on previous methods applied to the investigation of ancient white and colored marbles. Microscopic samples were taken from the painting with the aim of keeping both their size and mass at a minimum possible. All investigated samples consist of a highly complex, multi-layered, heterogeneous material, where the calcium carbonate aliquot is very limited. The investigation has been carried out in a non-destructive way, registering the EPR spectra of the fragments, identifying the diagnostic Mn(II) spectra, parameterizing them, and comparing them with the most extensive available database through a set of robust statistical methods. The main results include the attribution to calcite (marble rather than chalk), the mineralogical speciation of the carbonate layer and the reduction of the possible calcite provenance sites to few localities where marble was exploited. Among them, the marble from Apuan Alps is one of the likely provenances of this calcite.