Characterization of Mexican Amber from the Yi Kwan Tsang Collection

Twenty-seven amber samples from an important collection of 115 specimens from Chiapas, Mexico, were subjected to gemmological analysis, microscopy of the inclusions (including taxonomic classification), infrared spectro-scopy, X-ray powder diffraction (XRD) and mass spectrometry. Some of the data were compared to those obtained from amber samples from the Baltic Sea and the Dominican Republic. All the ambers had the same RI (1.54), but the Mexican samples showed slightly lower SG values (1.03) than the Dominican (1.05) and Baltic (1.06) ones. Mexican amber is notable for hosting a large variety of beautiful organic inclusions, in particular flower petals and leaflets of the extinct species Hymenaea mexicana, as well as a planthopper of the extinct species Nogodina chiapaneca, which dates back to the Middle Miocene and has been found only in amber from Chiapas. XRD analysis of samples from all three localities showed the expected amorphous pattern accompanied by traces of refikite and hartite, as well as calcite in the Mexican samples. Infrared spectroscopy was useful for identifying amber from each of the three localities. Mass spectrometry of the Mexican (and Dominican) amber showed that it lacked succinic acid and can therefore be classified as a resinite of Class IC (i.e. resinites with ozic acid and/or zanzibaric acid derived from the Hymenaea genus).