Egyptian sculptures from Imperial Rome. Non-destructive characterization of granitoid statues through macroscopic methodologies and in situ XRF analysis

摘要

Aegyptiaca-like Domitian's obelisk is now decorating Bernini's fountain on Piazza Navona or the Egyptian lions flanking Michelangelo's stairs towards the Capitol figure prominently amidst Rome's cultural heritage. Motivations for the import, contextualization, and copying of these objects during the Imperial Roman period are as heavily debated as they are ill understood. Provenance determination plays an important role in these discussions in terms of a (supposed) dichotomy between Egyptian (real) versus egyptianising (copy) but has only been applied stylistically and never been tested analytically. A scientific characterization of the materials themselves is even lacking altogether, as is an investigation into the cultural and symbolic meaning of the materials used. This paper is a first attempt to address these important lacunae on the basis of an explorative study of a selected sample of Egyptian statues from Rome. The identification and provenance attribution of the materials used for these statues are often problematic due to their relatively fine-grained nature and dark color. Therefore, a full non-destructive analysis of Egyptian statues in dark-colored rocks is presented in this study, with the stones evaluated by macroscopic examination and handheld X-ray fluorescence (XRF) analysis. The implemented methodology has allowed a distinction between greywacke and several varieties of granitoid rocks. In order to evaluate the potential for source attribution, a comparison was made between the results of our analyses and geochemical data for several granitoid rocks from Egypt. This has suggested Aswan as most likely source. The results presented here indicate that handheld XRF analysis can be used for the assessment of compositional variability in and potentially for the provenance of granitoid rocks, provided that a fine-grained area of the material can be measured on multiple locations, and if these values can be assessed on (in)consistencies with other published reference materials.