Bronze Age vitreous materials from Punta di Zambrone (southern Italy)
Résumé
This study presents the results of an archaeometrical investigation of Bronze Age vitreous materials from the archaeological site of Punta di Zambrone (Calabria, southern Italy). The analyses of a set of samples (9 faience beads, 1 glassy bead) from approximately 1200 BCE (Recent Bronze Age) were carried out with an environmental scanning electron microscope (ESEM) and LA-ICPMS (for the glassy bead) following a non-destructive protocol. Only very small chips of faience were sampled for X-ray powder diffraction (XRPD) and preparation of thin sections for ESEM analysis. The glassy bead is an opaque light-blue silica-soda-lime type with an uncommon chemical composition, comparable to some coeval Italian and Mycenaean glassy faience artefacts. These are called LMLK (low magnesium low potassium) glassy faience, but the flux used for their production has not yet been identified. The trace-element analysis allows exclusion of a Mesopotamian or Egyptian provenance for this sample, suggesting it was produced with rather impure raw materials. The nine faience beads have suffered from extensive weathering. The microstructural examinations carried out with the ESEM enabled definition of three different groups: (1) light beads consisting almost entirely of quartz crystals without any original interparticle glass, which could be due to the heavy weathering; (2) dark beads with a high content of manganese and iron oxide and scarce presence of interparticle glass in the body, suggesting the original presence of Mn/Fe-rich interparticle glass; this presence indicates that a glazing mixture containing alkalis and colorants was mixed with quartz, therefore the efflorescence method could have been used for glazing, in combination with either cementation or application glazing (hybrid glazing methods); and (3) one green sample exhibiting an heterogeneous body rich in Mg, K, Ti, and Fe but not containing Mn. The XRPD analysis of a faience bead of group 1 confirmed the exclusive presence of quartz, whereas for group 2, an additional small peak compatible with Mn oxide (Possibly hausmannite) was observed. Considering the colorant used for the dark beads, the Zambrone faience beads can be compared to Mesopotamian and Minoan faience beads. They belong to a type widespread in north-central Italy between the Middle and Late Bronze Age, and in southern Italy between the Early and Late Bronze Age. The same type of faience is found in the Aegean from the middle of the 3rd millennium BCE to the 12th century BCE.