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Heat-induced color changes of fossilized Miocene mastodon ivory (13-16 Ma) have been known at least since the Middle Ages. Cistercian monks are believed to have created odontolite, a turquoise- blue “gemstone,” by heating mastodon ivory found in Miocene geological layers next to the Pyrrenean chain, France, to use it for the decoration of medieval art objects. This material has been the object of investigations of famous European naturalists and gemmologists, among them Réaumur (1683-1757). Although vivianite [Fe3(PO4)2·8H2O] is the commonly accepted coloring phase supposed to appear when heating fossilized mastodon ivory, our previous spectroscopic studies using PIXE/PIGE and TEM-EDX demonstrated that the chemical composition of collection odontolite and heated mastodon ivory corresponds to well-crystallized fluorapatite [Ca5(PO4)3F] containing trace amounts of Fe (230-890 ppm), Mn (220-650 ppm), Ba (160-620 ppm), Pb (40-140 ppm), and U (80-210 ppm). No vivianite has been detected.

Heat-induced color changes of fossilized Miocene mastodon ivory (13-16 Ma) have been known at least since the Middle Ages. Cistercian monks are believed to have created odontolite, a turquoise- blue “gemstone,” by heating mastodon ivory found in Miocene geological layers next to the Pyrrenean chain, France, to use it for the decoration of medieval art objects. This material has been the object of investigations of famous European naturalists and gemmologists, among them Réaumur (1683-1757). Although vivianite [Fe3(PO4)2·8H2O] is the commonly accepted coloring phase supposed to appear when heating fossilized mastodon ivory, our previous spectroscopic studies using PIXE/PIGE and TEM-EDX demonstrated that the chemical composition of collection odontolite and heated mastodon ivory corresponds to well-crystallized fluorapatite [Ca5(PO4)3F] containing trace amounts of Fe (230-890 ppm), Mn (220-650 ppm), Ba (160-620 ppm), Pb (40-140 ppm), and U (80-210 ppm). No vivianite has been detected.

Abstract Raman spectroscopic measurements on synthetic air clathrates, prepared at different pressures and temperatures, are presented. The gas fractionation for clathrates formed at -2 and -20°C is determined from the integrated vibron mode intensities of nitrogen and oxygen molecules. An increasing fractionation in favour of oxygen with increasing pressure is found. An asymmetric peak shape for the O2 vibron mode was observed in air clathrates prepared at 300 bar and -2°C. The asymmetry of the N2 vibron mode in the same sample is much less pronounced