Conventional flat plate-shaped brushite, dicalcium phosphate dihydrate, CaHPO4 center dot 2H(2)O), produced by reacting Ca-chloride and alkali phosphate salt solutions, were found to undergo a maturation process (changing their Ca/P molar ratio from 0.8 to the theoretical value of 1) similar to those seen in biological apatites. Water lily (WL)-shaped brushite crystals were produced in nonstirred aqueous solutions at room temperature in 24 h, by using precipitated calcite and NH4H2PO4 as the starting chemicals. The hydrothermal transformation of WL-type brushite into octacalcium phosphate (OCP) or Ca-deficient hydroxyapatite (CDHA) was tested at 37 degrees C by using four different biomineralization solutions, including Tris-buffered SBF (synthetic body fluid) and sodium lactate-buffered SBF solutions. All four solutions used in this study consumed the starting brushite in 1 week and caused transformation into a biphasic mixture of nanocrystalline OCP and CDHA of high surface area. WL-type brushite crystals when synthesized in the presence of small amounts of Zn2+ ions resulted in the formation of, for the first time, spherical micro-granules of brushite. Synthesis of brushite in spherical form was difficult prior to this study.