#calcium phosphate

• Apatite — A mineral from the phosphate class, representing a natural calcium phosphate that contains fluorine, chlorine, or hydroxyl groups within its crystalline structure. This compound is widely used in industry as the primary raw material for producing phosphate fertilizers and phosphoric acid, while also being the most common phosphate mineral in the Earth's crust.
• Apatite — The standard literary and most frequent form of the name of the natural phosphate mineral; it also represents a major structural component of hard tissues in human and animal organisms, found as hydroxyapatite as the core mineral within the structure of tooth enamel and bones.
• Ardealite — A very rare secondary phosphate mineral, structurally composed of hydrated calcium phosphate-sulfate, with the chemical formula Ca2(PO4)(SO4)·4H2O. It typically forms as an alteration product in cave guano deposits through the reaction of acidic phosphate solutions with surrounding limestone, first discovered and described in 1932 in the Cioclovina Cave in Hunedoara County, Romania, from which it derives its name structurally linked to the Ardeal region.