Mineralogical and chemical changes that accompany early stages of weathering are described from a tropical climate in Uganda. The weathering product of a granitic gneiss and an amphibolite was analysed mineralogically by X-ray diffraction and chemically by X-ray fluorescence. While the amphibolite weathers into essentially kaolinite and iron oxides the weathering product of the granitic gneiss includes quartz, illite, mixed layered minerals and smectite in addition to kaolinite. It is concluded that the stability of clay minerals formed during weathering is not only a function of precipitation but is also dependent on the composition of the parent rock.
Mineralogical and chemical changes during weathering of acid and basic rocks in Uganda.