The mineral of bone.

This is a review of the chemistry and structure of synthetic, mineral, and biologic hydroxyapatites. Bone apatite has a large, reactive specific-surface and is characterized by its crystal imperfection and non-stoichiometry. Precipitated and bone hydroxyapatites are in the submicroscopic size range where their solubility decreases rapidly with a small increment of crystal growth. A discussion is given of the various mechanisms proposed for tissue mineralization. The body seems to contain a number of nucleating and inhibiting mechanisms which seem to work in concert, possibly providing redundant pathways to the mineralization of tissue.