The over-all problem of precipitated tricalcium phosphates is important to the fertilizer industry, to the chemist charged with water defluorination, and in chemical and biochemical investigations. Because of existing uncertainty in the composition and properties of commercial precipitated tricalcium phosphates, seven samples were obtained from dependable vendors and submitted to chemical, optical, powder diffraction, Neubauer tests, and pot culture studies. Monocalcium phosphate, five purchased dicalcium phosphates, and three prepared tertiary products were included as controls. The dicalcium phosphates were virtually citrate-soluble and of uniform P205:Ca0 ratio.The tertiary precipitates varied in composition, solubility, and reactivity toward calcium fluoride, in optical properties, in x-ray powder diffractions, in Neubauer tests, in plant response, and in P206 recovery.