* Calcium phosphate (Ca₃(PO₄)₂): This provides the calcium and phosphate ions that form the basic structure of the mineral.

* Calcium hydroxide (Ca(OH)₂): This contributes the hydroxide ions (OH⁻) that give hydroxyapatite its name and unique properties.

While these are the main components, trace amounts of other elements, like fluoride, chloride, and carbonate, can be incorporated into the hydroxyapatite structure.