Pietro Moioli

Obsidian use in the mosaic of the St. Juvenal church, Narni (Italy): chemical characterization and origin

Tesserae from the mosaic on the front of the San Giovenale chapel inside the Narni Cathedral were analyzed through non-destructive XRF analysis for the characterization of both colouring matters and opacifiers of the glass matrix. Subsequently, the concentration of the elements present at trace levels (μg g-1) was determined by means of Instrumental Neutron Activation Analysis (INAA) for comparisons with obsidians of known provenance and well-studied micro-elemental composition, in order to identify the geographical origin of the obsidian used in this Middle Ages mosaic. The main result is that the black tesserae were made with obsidian fragments coming from the Sardinia deposits (probably, Arci Mountain site C).

Replicas in Caravaggio's paintings: the correct use of scientific analysis

Painting techniques and materials employed by Caravaggio are analyzed by X-ray fluorescence and radiography of unquestioned genuine works and compared to replicas of his earlier work. This approach is important in the attribution of recently discovered paintings and copies from the XVII century.