Argillaceous rocks can display a wide range of durability behavior after excavation and in cut slopes. In this paper, we propose a classification of argillaceous rocks based on their textural characteristics. Three main components of the classification scheme are the clastic framework, the fine-grained matrix, and the cementing agent. Unlike other schemes, the unlithified argillaceous sediments are included as well. The names proposed for the rocks broadly follow the existing nomenclature used in petrographic classifications. The durability of some argillaceous rock types has been assessed by taking into account a set of degradation features of the excavated slopes. It has been observed that the ratios of these textural components exert a strong control on the long-term durability of slopes.