Ca(10)(PO(4))(6)(OH)(2) was pptd. from aq. solns. of H(3)PO(4) and Ca(OH)(2), dried at 105 degrees C in air, at -67 degrees C for 72 h or at 50-90 degrees C under vacuum, calcined at 750 degrees C for 30 min and studied for microstructure, chem. compn., sp. surface and mass loss during DTA. The product dried by lyophilization showed the highest sp. surface before calcination.