Lucerne “africane” da Egnatia: importazioni e imitazioni, tra archeologia e archeometria

Late Roman oil lamps from the archaeological site of Gnatia (Fasano, BR) have been investigated with different complementary analytical techniques. Chemical and morpho–mineralogical analyses have been carried out on ceramic bulk and covering of 40 oil lamps, which from a stylistic point of view can be classified in part as African imports and as local production (Atlante X, XIII, XV). The aim of the study was identifying the true provenance of the finds, defining technological level and clarifying trade relations between Egnazia and the Mediterranean Basin. Morpho–mineralogical investigation has been performed by polarized–light Optical Microscopy (OM), Scanning Electron Microscopy (SEM) with Energy Dispersive Spectrometry (EDS) and chemical analysis by Inductively Coupled Plasma Mass Spectrometry (ICP–MS). Multivariate statistical techniques, such as Principal Components Analysis and Clustering Analysis, have been used for treating the compositional data matrix, in order to compare chemical and morpho-mineralogical features with stylistic and typological ones. The analytical results on the ceramic bodies allow us to correctly classify the finds, shedding light on the use of different raw materials compatible with a provenance from North Africa, Northern and Central Tunisia and Egnatia respectively. Moreover, morpho-mineralogical analysis on surfaces of the import oil lamps has highlighted two different production technologies: most import items have shown no clayey slip, so the brightness is due to a superficial polish process before firing; a few import samples show a superficial slip layer, probably obtained by refining the clay used for the body. As concern locally produced lamps, a superficial slip layer, realized with a clay different from that used for the ceramic body, is present on type Atlante X only.