Zirconium mobility in bauxites of Southern Brazil

A geochemical study of the behaviour of zirconium in bauxites developed on alkaline rocks in southern Brazil is presented. Zirconium, generally considered as an immobile element during weathering, shows an important mobility conditioned to the original Zr bearing parent mineral. In the two areas (Poços de Caldas and Lages) zircon is rare and the zirconium bearing parent minerals are complex weathered silicates as “giannettite”, eudyalite, astrophyllite, etc. Since the first stages of weathering, zirconium is partially leached of from the bauxite profile and the remaining Zr is incorporated in secondary phases of the bauxite (amorphous ferric oxydes and aluminous goethite).