Archaeometric investigation of Roman tesserae from Herculaneum (Italy) by the combined use of complementary micro-destructive analytical techniques

Vitreous tesserae from two mosaics in Herculaneum (Italy) dating from the 1st century AD have been investigated in order to gather information on Imperial Age opaque glass. The combined use of complementary micro-destructive analytical techniques, namely optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), inductively coupled plasma-mass spectrometry (ICP-MS), transmission electron microscopy (TEM), and X-ray powder diffraction (XRPD) allowed to define the nature of formers, fluxes, chromophores and opacifying compounds and to determine the type of raw materials employed for their introduction. The results confirmed the high technological level of Imperial Age glassmakers and clarified some details of the production processes. Experimental data have been obtained concerning formation of antimony-based opacifiers. The presence of tin-containing Ca- and Pb-antimonates has been ascertained in various green, yellow and turquoise tesserae. Moreover, unusual divergences from the established Roman age ‘low magnesia–low potash’ (LMLK) glass composition have been found for some red and green samples.     

Lapis lazuli usage for blue decoration of polychrome painted glazed pottery: a recurrent technology during the Middle Ages in Apulia (Southern Italy)

Seven fragments of atypical proto-majolica from the archaeological site of Siponto (Manfredonia, Foggia) were analysed by chemical and physical methods. All fragments have blue, brown and yellow painted decorations. Raman microscopy and Scanning Electron Microscopy–Energy Dispersed Spectroscopy (SEM–EDS) investigations identified the blue pigment to lapis lazuli. We previously identified this mineral in the blue coloration of the tin–lead glaze of proto-majolica finds at other Medieval sites in Apulia (Castel Fiorentino and Lucera). The discovery of the fragments from Siponto, in spite of their peculiar technological-decorative features, proves that the use of lapis lazuli as a ceramic pigment was not an isolated occurrence, but was quite common in the Middle Ages in the production of typologically heterogeneous ceramics in Southern Italy.     

Technological features of Apulian red figured pottery

Apulian red figured pottery samples, dating back to the 5th and 4th centuries BC, from the archaeological site of Monte Sannace (Gioia del Colle, Bari, Italy) have been characterized from the physical–chemical, mineralogical and morphological points of view. Scanning electron microscopy, X-ray diffraction and atomic spectroscopy investigations have been carried out on the ceramic body, red decorated area and black gloss of the fragments, with the aim of outlining the technological features and of defining the nature of coatings and decorations. All 5th century fragments show the same features: fine texture of the ceramic body, red figures saved from the ceramic paste and black gloss painted directly on the ceramic body. The statistical treatment of compositional data of ceramic bodies excludes the local production of these objects. As regards the 4th century fragments, some show similar features to the 5th century ones; however others are characterized by the coarse texture of their ceramic body and an intermediate red layer of finer clay between the black gloss and the ceramic body. The analytical results make it possible to distinguish two different production technologies of red figured Apulian vases in Monte Sannace during the 4th century BC. Certain vases were produced using the “classic” Attic technology and others with a different technique, not previously known, which involved the application of a red engobe layer on the clay paste, before the black gloss painting.     

Oil Lamps from the Catacombs of Canosa (Apulia,Fourth to Sixth Centuries AD): Technological Features and Typological Imitation

Fifty oil lamps from the catacombs of ‘Ponte della Lama’ (Canosa di Puglia, second to sixth centuries ad ) were analysed to understand the correlations existing between types and fabrics and to determine their provenance. Petrographic and chemical analyses confirmed the archaeological hypothesis of local production of the oil lamps, using fluvial deposits. However, the three samples of oil lamps imitating the African ‘Atlante VIII’ are considered chemical outliers compared to the rest and are supposedly of foreign origin. The extensive and original repertory of lamp types characterizes Canusium as the production centre in the late Roman period.