Morphological changes occurring in naturally weathered micas in seven residual soils from Ontario were studied. Splitting, exfoliation of the (100) planes, surface coats, filling of spaces with soil material as well as cracking and crumbling of (001) surfaces were the main morphological changes found to be taking place during natural weathering of mica particles. The significance of the observed feature in relation to the general theory of mica weathering is discussed.