| Abstract: | Amber, a class of fossil resins, comprises largely terpenoid components. The structure of the major, insoluble portion has not been defined previously. We report the analysis of European amber by carbon-13 nuclear magnetic resonance spectroscopy directly on solid samples. Two major types are defined, depending on the appearance of the alkene resonances. Baltic amber (succinite), along with other northern ambers such as gedanite, has a pronounced resonance from an exomethylene group. The southerly ambers (rumanite, schraufite, walchowite, delatynite and true simetites) lack the exomethylene resonances. The succinite group gives spectra consistent with a labdane-type precursor and the rumanite-like ambers give spectra consistent with an abietane-type precursor. These results are best explained by at least two different palaeobotanical sources of the fossil resins. |
