Location of mineral salts in bone?

Mineral salts are stored in the hydroxyapatite crystals of the bone matrix. Calcium and phosphate ions are the main components of hydroxyapatite, but other ions such as magnesium, sodium, potassium, and carbonate are also present. The hydroxyapatite crystals are arranged in a repeating pattern called the "bone lattice". This lattice gives bone its strength and hardness.