Topic summary
Argillaceous
Extracted from the Wikipedia article Clay mineral.
Argillaceous rocks
Argillaceous rocks are those in which clay minerals are a significant component. For example, argillaceous limestones are limestones consisting predominantly of calcium carbonate, but including 10–40% of clay minerals: such limestones, when soft, are often called marls. Similarly, argillaceous sandstones such as greywacke, are sandstones consisting primarily of quartz grains, with the interstitial spaces filled with clay minerals.