Epitaxial considerations in urinary stone formation. II. The oxalate-phosphate system.

We examined epitactic relationships between hydroxyapatite (HAP) and the hydrates of calcium oxalate from a crystallographic point of view. We also examined the growth of HAP on the calcium oxalate surfaces at a constant supersaturation, we maintained by the controlled addition of solutions containing the lattice ions of the precipitating phase. Calcium oxalate trihydrate was the only salt that induced HAP overgrowth. The latter phase, however, was found to be a suitable substrate for the growth of calcium oxalate monohydrate.