The correct name is Microcrystalline Hydroxyapetite Compound (MCHC) sold in India under the trade name of Ossopan. It is derived from bovine bones and contains calcium, phosphates, trace elements of fluoride, protein, glycosaminoglycans etc. MCHC can also be derived from marine coral for use in the construction of orbital implants. It is no different than synthetic calcium supplements except that it is probably more easily assimilated. There no published reports of unacceptable adverse effects on chronic use.