The iron(III) phosphate strengite, FePO4,2H(2)O, has been precipitated at 25 degrees C by mixing solutions of iron alum and ammonium phosphate. The rate of crystallization has been determined by pH recording. Three stages of crystal growth kinetics could be distinguished: (1) mononuclear growth, (2) polynuclear growth and, in a few cases, (3) spiral growth (BCF mechanism). From the first two, the value of edge free energy lambda = 87 +/- 1 pJ/m was found. The identity of the precipitate was verified by SEM, XRD and Mossbauer spectroscopy. (C) 2017 Elsevier B.V. All rights reserved.