Final answer:
Hydroxyapatite is composed of calcium, phosphorus, and oxygen. It is a key mineral in bone structure, providing strength and hardness through a process called calcification.
Step-by-step explanation:
The elements present in hydroxyapatite, Ca5(PO4)3OH, include calcium, phosphorus, and oxygen. Hydroxyapatite is a mineral that is crucial for bone strength and hardness. It forms by the combination of calcium phosphate salts that crystallize on collagen fibers. The deposition of these mineral salts is known as calcification. While the mineral can incorporate other elements such as magnesium and fluoride, the primary components of hydroxyapatite itself are calcium, phosphorus, and oxygen.