The apatite crystal lattice is very common, but not very well known. Hydroxyapatite, (HA) Ca10 (PO4)6(OH)2 , is the 'hydrogen atom' of the mineral component of mammalian bone and tooth. In its natural mineral form it is prized as a source of phosphate fertilizer. Since the metal, phosphate, and hydroxyl groups can be readily substituted by ion exchange, HA is valued as a filtrant for trapping toxic metals, and as a slow-release source of beneficial ions. Properly doped HA can be used as an efficient 'green' catalyst operating a low temperature.
The following pages show a little of our group's work in this expanding field.