Mudstone is a fine-grained sedimentary rock composed primarily of clay and silt-sized particles. It is often formed in low-energy environments such as deep marine basins, lakes, and floodplains. Mudstone is significant in understanding depositional environments, the preservation of fossils, and the geochemical cycles of elements.
Source Potter, P. E., Maynard, J. B., & Depetris, P. J. (2005). “Mud and Mudstones: Introduction and Overview.” Springer.