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. MCHA contains highly absorbable calcium and phosphorus, which are the major mineral components of bone. NOW Bone Strength is a comprehensive bone support product with MCHA. it also provides magnesium and other important minerals, as well as vitamins C, D, and K to aid in the synthesis and maintenance of bone tissue. NOW Microcrystalline Hydroxyapatite (MCHA) is derived exclusively from Australian cattle.