Fe(II-III) hydroxysalt green rusts;: from corrosion to mineralogy and abiotic to biotic reactions by Mossbauer spectroscopy

Fe(II) - Fe(III) hydroxysalts commonly called green rusts are layered double hydroxides of formula [Fe-II (1-x) Fe-x(III)(OH)(2)](x+) .[(x/n) A(n-) .(m/n) H2O](x-) constituted of brucite-like layers containing Fe cations in the centres of OH- octahedrons and interlayers, which anions and water molecules belong to. They play a key role in corrosion and environmental sciences as well as mineralogy since they are, on the one hand, intermediate products between Fe( II) and Fe( III) states and, on the other hand, can be the major iron-bearing mineral in hydromorphic gley soils. Their crystal structure, Mossbauer spectra, methods of synthesis, abiotic as well as biotic, and some applications are presented here.