Comparative analysis of odontolite, heated fossil ivory and blue fluorapatite by PIXE/PIGE and TEM

PIXE/PIGE trace elements analyses of odontolite, fossilised ivory as well a s blue and yellow geological fluorapatite are presented in order to underst and the blue colour origin. We also compare PIXE/PIGE micro-mapping with a resolution of about 100 mu m on a heated fossil ivory sample and on archaeo logical odontolites. Complementary structural analyses with TEM are perform ed. Comparison of crystal sizes and morphologies in heated fossil ivory to those of odontolite and fluorapatite enables to conclude on a previous heat process. Colour of the archaeological odontolite samples was the result of thermal process of fossil ivory which probably involves apatite transforma tion into blue Ca-5(PO4)(3-gamma)(MnO4)(gamma)F. (C) 2000 Published by Else vier Science B.V. All rights reserved.