Di bronzo e corallo: studio archeometrico di oggetti di ornamento da siti archeologici piemontesi dell'età del Ferro

The preliminary results of a multi-analytical archaeometric study on bronze artefacts adorned by white-to-reddish inlays and/or linear decorations of presumed coral are presented here. These artefacts are documented in the Early Iron Age (8th-6th century BC) in the area of the Golasecca Culture and in general in Northern Italy. These include, for example, the Longone al Segrino pendants and leech fibulae with circular insets and/or lines. Although the material forming these insets is identified in the archaeological literature as red coral (Corallium rubrum), scarce scientific analyses have been carried out to support this hypothesis. The development of a specific, totally non-destructive multi-analytical protocol proved to be extremely useful in achieving an exhaustive characterisation of these materials, as well as in identifying the possible use of specific raw materials and organic binders. The case study presented here concerns bronze fibulae with circular decoration from the archaeological site of Pombia (NO). The performed archaeometric analyses (optical microscopy, µ-Raman spectroscopy and SEM-EDS) made it possible to identify presence of calcite in 4 out of the 5 studied artefacts, with variable magnesium content (from zero to 2.2%, expressed as number of atoms). These results may indicate the potential use of a material different from C. rubrum (e.g., calcite, fossil coral, white coral), or else that red coral might have undergone specific alteration processes in time – i.e., during interment of the artefacts.