Corrosion of ancient Chinese bronze money trees studied by Raman microscopy

Raman microscopy was used to identify corrosion products and their location s on and within samples from ancient Chinese bronze money trees to help det ermine the corrosive environments the trees experienced in the past. The co mpounds found included Cu2O, CuCO3 . Cu(OH)(2), 2CuCO(3) . Cu(OH)(2), PbO, PbCO3 and PbSO4. In addition, a number of pigments on the exterior were ide ntified (ultramarine, Prussian blue, phthalocyanine blue, phthalocyanine gr een, Hansa yellow G and chrome yellow) which were applied to the artifacts in more recent times. Two-dimensional Raman mapping was applied to cross-se ctions of the artifacts to determine the spatial extent of corrosion produc ts in the interior and to investigate the selective corrosion of different phases of the bronze. Raman microscopy is shown to be a useful tool to comp lement more traditional characterizations such as scanning electron microsc opy and x-ray energy-dispersive spectrometry in the analysis of metal artif acts. Copyright (C) 1999 John Wiley & Sons, Ltd.