In human anatomy, what is the main mineral component of bones and teeth?

In human anatomy, hydroxyapatite is the main mineral component of bones and teeth.

Hydroxyapatite is a crystalline calcium phosphate with the formula Ca10(PO4)6(OH)2. In living tissue, bone mineral is not perfectly pure or uniform; it contains small substitutions and is often described as biological apatite. The crystals are deposited within a framework of collagen fibers.

Collagen gives bone much of its tensile flexibility, while hydroxyapatite provides hardness and resistance to compression. Teeth contain hydroxyapatite too, especially in enamel, where the mineral content is higher than in bone. This combination explains why enamel is exceptionally hard.

Bone is constantly remodeled by osteoblasts, which build bone, and osteoclasts, which resorb it. Calcium and phosphate metabolism is regulated by several hormones, including parathyroid hormone and vitamin D. Acidic conditions can dissolve hydroxyapatite, contributing to dental erosion and demineralization.