Ar`gil*la"ceous (#), a. [L. argillaceus, fr. argilla.]
Of the nature of clay; consisting of, or containing, argil or clay; clayey.
Argillaceous sandstone Geol., a sandstone containing much clay. -- Argillaceous iron ore, the clay ironstone. -- Argillaceous schist or state. See Argillite.
© Webster 1913.