The electrokinetic behaviour of freshly prepared γ- and α-FeOOH

α-FeOOH and γ-FeOOH have been prepared in different ways and their electrokinetic behaviour was investigated. Dilution of the solution containing the components from which the minerals were synthesized led to a decrease of the isoelectric point (pH) of these substances. Drying of the moist preparations had the same effect. These results have been correlated with those from Rontgenographic and differential thermal analysis of the preparations.