Di bronzo e corallo, studio archeometrico di oggetti di ornamento dalla necropoli dell'età del Ferro di Pombia

The paper presents the preliminary results of a multi-analytical archaeometric study of bronze artefacts with reddish-white inlays or linear decorations in presumed coral. The use of coral is documented in the Early Iron Age (8th-5th century BC) in the area of the Golasecca Culture and in general in Northern Italy: e.g., the Longone al Segrino-type pendants and leech fibulae with circular insets and/or lines. Although this whitish material is identified in the archaeological literature as red coral (Corallium rubrum), very few scientific analyses have been carried out to support this hypothesis. The development of a specific, totally non-destructive multi-analytical protocol proved useful in obtaining a comprehensive characterisation of the material, identifying the nature of the raw material and the possible use of organic binders. The case study presented here concerns bronze fibulae with circular inserts from the necropolis of Pombia (NO). The archaeometric analyses carried out (optical microscopy, μ-Raman spectroscopy and SEM-EDS) allow presence of calcite to be identified in 4 out of 5 analysed artefacts, with a variable Mg content (from zero to 2.2%, expressed as atomic percentage). These results may indicate either the potential use of a material other than Corallium rubrum (e.g. calcite, fossil coral, white coral), or that the red coral may have undergone specific alteration processes in diagenesis (i.e., during interment of the artefacts).