Two major stages of clay mineral alteration and porosity development are present in the weathered Nygård kaolin pit. Horizontal changes in the fabric of samples less than 3 m apart illustrate the high variability of closely spaced samples. The weathering profiles in the Nygård kaolin pit can be correlated with reservoir rock fabrics from fields on Utsira High. The mineralogical key to predicting a potential reservoir is the presence of halloysitic, poorly-ordered kaolinite.