The two years GOSSAN project (GOethite in Supergene Systems: ANalysing trace element substitution goethite and related iron oxides and oxyhydroxides) was aimed to the study of geochemical, morphological and structural composition of natural of iron oxides and oxyhydroxide in different types of Supergene Ore deposits (SOD). The main objective was the investigation of the behaviour of a range of economic metals commonly occurring in the primary ore deposits subjected to re-mobilization processes taking place during the weathering followed by their quantification within the natural oxides and oxyhydroxide, with major attention to the goethite. The main motivation for studying goethite as main mineral, is ascribable to several reasons: i) it is the most stable mineral among the Fe-oxi-hydroxides; ii) it is always present in the oxide zones of supergene ore deposits; iii) it is rarely pure: in fact, conspicuous amounts of cations isovalent or heterovalent to Fe3+ i.e. Ni, Zn, Co, REE, Sc, Ga, Ge, In, Pb, Hg, Mn, Cd, Si, Al etc. can substitute the Iron or be incorporated in the goethite structure (α-FeOOH). Some of the above mentioned metals were defined as “Critical Elements” by EU (
https://ec.europa.eu/growth/sectors/raw-materials/eip_en/en/content/strategic-implementation-plan-sip-0(s’ouvre dans une nouvelle fenêtre)) which remarked their importance in the new generation technologies and industrial development; on the contrary, other (i.e. Hg, Pb, Cd..) are considered as “problematic elements” in term of environmental and human health. Hence, an accurate knowledge of their behaviour, distribution and a systematically investigation on their occurrence in the mineral phases commonly present in SOD soils in addition to the definition of their economic potential is crucial for the modern and future society.
