Mobilidade de cátions em altera？？o intempérica de diabásio no município de Rio das Pedras, SP

the mobility of the principal cations of a diabase is studied in a weathering sequence, from unaltered rock to the rock-derived soil. from the original rock, just about 44% of the original rock material remains in the final fase, making up the detrital fraction of the soil. elimination of the soluble cations is fast and occurs in the early weathering stages. silica, which is removed at a slower rate is eliminated up to about 60% of the original rock content, while aluminium, iron and titanium stay in the soil.