ZIRCONIUM MOBILITY IN BAUXITES OF SOUTHERN BRAZIL

A geochemical study of the behaviour of zirconium in bauxites develope d on alkaline rocks in southern Brazil is presented. Zirconium, genera lly considered as an immobile element during weathering, shows an impo rtant mobility conditioned to the original Zr bearing parent mineral. In the two areas (Pocos de Caldas and Lages) zircon is rare and the zi rconium bearing parent minerals are complex weathered silicates as ''g iannettite'', eudyalite, astrophyllite, etc. Since the first stages of weathering, zirconium is partially leached of from the bauxite profil e and the remaining Zr is incorporated in secondary phases of the baux ite (amorphous ferric oxydes and aluminous goethite). Copyright (C) 19 96 Elsevier Science Ltd & Earth Sciences & Resources Institute