Figure 4From: Brownish alterations on the marble statues in the church of Orsanmichele in Florence: what is their origin? Sant’Eligio by Nanni di Banco ca.1417-1421. Polished cross section of a sample from a brown area. The images show the thin residues of the patina on the marble surface - visible illumination (a), and a strong fluorescence inside the stone between calcite crystals - UV illumination (b).Back to article page