BIOAPATITE:PAST AND FUTURE RESEARCH

Bioapatite has a long and checkered history. Characteristically associated with living forms and specifically found in vertebrate bones and teeth there is continued interest in its chemical and physical characteristics as a source and sink of an anazing range of chemical elements. A member of the most common calcium phosphate sub group that also contains fluorapatite and hydroxylapatite, bioapatites are difficult to identify accurately becasue of their exceedingly fine grain-size and variable composition. A major issue is the association of carbonate in the crystal structure, and that anions and cations can both be incorporated. These characteristics have been capitalized upon:bioapatites have been used as indicators of the environments in which they formed. Bioavailability of major (calcium and phosphorus) and minor, or trace (Mn,Fe, Pb) elements may be the first gate keeper for the incorporation and formation of bioapatites, but the mineral itself places some additional constrainst on the partitioning of particular elements. Recent trace metal studies in nutrition show many molecular biology techniques and knowledge. They provide more sophisticated approaches to establishing dietary requirements. The crystal chemical roles of bioapatite have not yet been factored into the homeostatic metabolic system and present an opportunity for biomineralogists.