Hydroxyapatite: a complex of calcium and phosphorus in bone

Bone is a living tissue that changes in response to physical stresses. Bone also encases the marrow, the source of many types of blood and immune cells, and it serves as the reserve note for minerals such a calcium and phosphorus.

When bones first develop, protein forms sort of scaffolding that filled in with the minerals calcium and phosphorus. Calcium and phosphorus are what bones hard and unlikely to break. While the collagen fibers to provide strength and flexibility.

Most of the calcium in bone is in the form of hydroxyapatite - a crystalline mineral complex of calcium and phosphorus.

Hydroxyapatite is the most important among the calcium compounds since it is found in natural hard tissues as mineral phase. Hydroxyapatite acts as reinforcement in hard tissues and is responsible for the stiffness of bone, dentin and enamel.
Hydroxyapatite: a complex of calcium and phosphorus in bone