Clastic Sedimentary Rock composed of clay and silt with clay domination with fissility properties.
The major difference from muddstone is that it has fissility properties.
See also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology + Petrophysics / Rock / Sedimentary Rock / Clastic Sedimentary Rock
[ Muddstone ]
[ Petrophysics / Volumetric Rock Model / Shaliness (Vsh) ]