Microcrystalline Hydroxyapatite (MCHA) is a compound that normally makes up the crystalline matrix of bone and teeth and is the substance that gives them their rigidity. Contains highly absorbable calcium and phosphorus, which are major mineral components of bone. This formula also provides magnesium and other important minerals along with vitamins C and D to aid in the synthesis and maintenance of bone tissue. NOW MCHA is derived exclusively from Australian cattle.