A white insoluble powder, Ca3(PO4)2; r.d. 3.14. It is found naturally in the mineral apatite, Ca5(PO4)3(OH,F,Cl), and as rock phosphate. It is also the main constituent of animal bones. Calcium phosphate can be prepared by mixing solutions containing calcium ions and hydrogenphosphate ions in the presence of an alkali:
It is used extensively as a fertilizer. The compound was formerly called calcium orthophosphate (see phosphates).