Raman spectroscopy of the basic copper chloride minerals atacamite and paratacamite : implications for the study of copper, brass and bronze objects of archaeological significance

Raman spectra of the basic copper chloride minerals atacamite and paratacamite were obtained at 298 and 77 K using a Raman microprobe in combination with a thermal stage. Four distinct regions involved with hydroxyl stretching, hydroxyl deformation, CuO stretching and CuCl stretching and bending were identified. The implication from the study is that Raman spectroscopy can be a useful tool for identifying corrosion products of copper, brass and bronze objects of archaeological or antiquarian significance. In addition, the technique may be a useful aid in the restoration degraded pigment products from old paintings.