C. Greffie et al., THE INFLUENCE OF GOLD ON THE CRYSTALLIZAT ION OF IRON OXI-HYDROXIDES, Comptes rendus de l'Academie des sciences. Serie II. Sciences de la terre et des planetes, 322(3), 1996, pp. 197-204
An experimental approach is used to characterize the role of gold duri
ng the formation of goethite and hematite from ferrihydrite. The resul
ts show that metallic gold colloids play a role during the maturation
of the gel at pH 7. In such conditions, the formation of goethite is r
etarded in presence of colloidal gold. Cold does not affect the format
ion of hematite. Dissolution/reprecipitation processes responsible for
the formation of goethite are slowed down by electrostatic effects of
the negative gold colloids on the concentration of Fe(OH); which coul
d be a rate limiting factor for goethite precipitation. Also Au-O-Fe s
urface complexes could slow down the formation of goethite.