What's the difference between apatite and hydroxyapatite?

Answer 1

Apatite, Ca5(PO4)3(OH,F,Cl) is a mineral group with the large anions (OH, F and Cl) in solid solution,freely substituting for each other. When the hydroxyl ion predominates (making your teeth white) then it is called hydroxyapatite. With fluorine predominating (making teeth hard, but colored brown) it is called fluorapatite and with chlorine predominating it is called chlorapatite. There isn't much potassium in apatite, despite what Keith said, but there can be other elements such as the Rare Earth Metals. Apatite is considered a "Trashcan" mineral due to the variety of elements that can be contained within its molecular structure.

Answer 2

Apatite is generally refered to as a group of minerals including flouroapatie, potassium-apatite, cacium-apatite (hydroxlapatite),ect. Hdroxylapatite is a particular type of calcium mineral in the apatite group.