The objective of this research is to characterize the nearest neighbor crystal structure environment around iron (Fe), strontium (Sr), lead (Pb), zinc (Zn), and other elements that occur in trace quantities and are incorporated into crystalline apatite in biological samples. The experimental technique of X-ray Absorption Fine-structure Spectroscopy will be used. The experimental technique X-ray Absorption Fine-structure Spectroscopy, a well established synchrotron technique, provides direct information on the crystal environment around an element. We can hypothesize about that crystal environment and its implications. If trace metallic impurities occupy substitutional sites they effectively replace another atom or basis set of atoms. The OH group in hydroxy apatite is sometimes substituted with the halogens F (fluoro-apatite) or Cl (chloro-apatite) and this may be the site of substitution in the bone crystal structure for trace metals. However, more likely a metal atom replaces the calcium atom in one of two non-equivalent calcium sites since the electronic configuration of the outer valence electrons of many metals is more similar to calcium than OH or other substitutional Hgroups or atoms.
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