Micro-Raman investigation of dangerous corrosion products of archaeological bronzes from Tharros (Sardinia-Italy)

A large number of bronze artefacts have been found during archaeological excavations carried out at Tharros (Sardinia, Italy). The composition of corrosion products have been determined by the combined use of optical microscopy (OM), micro-Raman spectroscopy (μ-Raman), scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). In particular, we will use μ-Raman spectroscopy to identify the corrosion products of natural patinas. This technique is equivalent or sometimes more efficient than microscopic and diffraction techniques to identify archaeological corrosion products. It is able to discriminate between different polymorphs, has a high spatial resolution and assures a correlation between the colour and the mineralogical nature. Furthermore has the advantage of being a nondestructive technique, quality highly valued in the cultural heritage.