Growth morphology and crystal habit of struvite crystals (MgNH4PO4 · 6 H2O)

The theoretical growth morphology of magnesium ammonium phosphate hexahydrate (struvite) crystals which build up about 15% of the renal and vesical calculi is established with the help of the periodic bond chain theory and compared to that of natural and synthetic crystals. The agreement is good; the faces of highest occurrence frequency correspond to the F faces 010, 001, 011, 012, 101, 110 and 111. Habit changes of crystals grown from pure aqueous solutions are shown to depend drastically on growth conditions (supersaturation). The relative development of complementary forms is discussed in relation to the non-centrosymmetry of the crystals.