Published online by Cambridge University Press: 09 July 2018
A recent article by Refait & Génin (1997) was devoted to Ni(II)-Fe(II)-Fe(III) pyroaurite-like hydroxychlorides obtained by aerial oxidation of mixed Ni(II)-Fe(II) hydroxides with various P = Fe/Ni ratios in chloride-containing aqueous solutions. Corresponding to the ideal composition Ni3-x IIFex IIFeIII(OH)8Cl.nH2O , the Fe(III)/[Ni(II)+Fe(II)] ratio is 1/3 when P is >1/3. These hydroxyehlorides oxidize quickly and the final product depends on P. In the absence of nickel, P = ∞, FeII 3FeIII(OH)8Cl.nH2O, known as Green Rust one (Bemal et al, 1959) oxidizes into γ-FeOOH. When P is >5/3, the X-ray diffraction (XRD) analyses of the end-product reveal lepidocrocite and some Ni(II)-Fe(III) hydroxychloride.