Description
Mudstone is an extremely fine-grained sedimentary rock consisting of a mixture of clay and silt-sized particles. Terms such as claystone and siltstone are often used in place of mudstone, although these refer to rocks whose grain size falls within much narrower ranges and under close examination these are often technically mudstones. Shale is often used to describe mudstones which are hard and fissile (break along bedding planes). Marl is often used to describe carbonate-rich soft mudstones.
Uses
Pottery: made from high-quality clays. Cement: made using mudstone and limestone.
Source