Two bauxitic profiles developed in similar topographic conditions where the vertical facies of weathering show a comparable evolution are here presented. Both profiles are the result of relative and absolute accumulation processes. One lies on granitic rock (Ivory Coast-Africa) and the other is on nepheline syenite rock (Passa-Quatro- Brasil). Mean data on the chemical composition in percentage of aluminium, iron, titanium and silicon are shown for the original rocks (granite and nepheline syenite) and also for their secondary products (bauxite). In both cases the weathering products show a similar Evolution despite the considerable chemical and mineralogical differences of the parent-rocks
