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Scanning Auger microscopy (SAM) has been used to study the surface and interface microchemistry of a sheet bronze belt from the Urartian kingdom in NE Syria of the early first millennium B.C. We find that the patina contains no copper species at all (decuprification), whereas carbonaceous species, Ca-silicates and N-bearing species are detected, the last being tentatively identified as organic (primarily amine-like) residues deriving from the soil. A textured grain, which we qualify as a second phase of bronze originated by an imperfect alloying of the two major metals (i.e., consisting of Cu-rich and Sn-rich domains) is observed on the metallic side lying beneath the patina. SAM imaging with a submicron spatial resolution highlights the presence of SnO₂ oxide inside what appears to be the hollow veins of the grain, whereas a Cu₂O-like oxide is confined exclusively to the flat regions of the grain. We explain these results by noting that the hollow veins, offering a higher exposure to external fluids, are likely to have promoted preferential formation of the more stable tin oxide over copper oxide. In another region of the metal side we studied the chemistry of grain boundaries and their surrounding areas. We find that S species lie exclusively inside the grain boundaries, whereas Sn and Zn species accumulate just outside the boundary channels, and this lateral chemical inhomogeneity is highlighted with a ~200 nm spatial resolution. Lateral segregation of Cu and Sn domains is imaged in another region with a spatial resolution of ~15 nm. This result marks the best spatial resolution any analytical method has yet achieved in highlighting chemical heterogeneities of ancient bronzes. Although archaeomaterials lie outside the mainstream applications of Auger techniques, this study provides convincing evidence that SAM can greatly advance our understanding of these materials, as it provides clues relating to corrosion and patination phenomena, as well as manufacturing processes that are not easily reachable by other microscopies or microanalytical techniques. ©2001 American Vacuum Society.