The tooth enamel of fossils of various ages and geological deposits has been analyzed by means of the laser raman microanalysis technique in order to follow the persistence of phosphate and carbonate ions during the fossilization process. The results obtained show that only the outer enamel is chemically stable and that problems with the middle and inner enamel are due to reprecipitation of crystallites in fossilization. The existence of fiducial levels of carbonate in inner enamel provides a unique basis for determining carbonate changes in archaeological sites. -- AATA