A multi-analytical approach for the assessment of the provenience of geological amber: the collection of the Earth Sciences Museum of Bari (Italy)

The Earth Sciences Museum of the University of Bari Aldo Moro (Italy) exhibits a wide collection of amber samples. These have been catalogued as Baltic amber (succinite), Sicilian amber (simetite), amber from New Jersey, Apennine amber and New Zealand copaline. However, some samples revealed to be erroneously classified as a consequence of incorrect information on the labels or in the museum catalogue. This may be due to historical forgeries, as is often the case of simetite, or to a possible exchange of samples that probably occurred during the displacement of the museum collection from the Central University Building to the Geo-environmental and Earth Sciences Department. In this study, all amber samples were systematically investigated with long wave UV rays, attenuated total reflectance (ATR), Fourier transform infrared (FTIR) spectroscopy and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) using on-line thermally assisted hydrolysis and methylation. The combined use of the latter two analytical techniques allowed for a complete characterisation of the ambers, whereas UV fluorescence showed to be of little value. The compositional data could be used for a better classification and valorisation of the amber samples of the museum collection. Two of the purported amber samples were shown to be copal, while four others are ambers but had been wrongly classified. Moreover, for some samples, it could be established that they had been subjected to treatment with a drying oil.