1.1 This specification covers chemical and crystallographic requirements for hydroxylapatite intended for surgical implants. For a material to be called hydroxylapatite, it must conform to this specification. (See Appendix X1.) This specification covers chemical and crystallographic requirements for hydroxylapatite intended for surgical implants. Elemental analysis for calcium and phosphorus will be consistent with the expected stoichiometry of hydroxylapatite. The calcium an