Texture (grain size, shape, sorting): Fissile (splits easily into layers); no visible grains Composition (detrital, biochemical, chemical): Detrital sediment grains; derived from the mechanical and chemical weathering of continental rocks, which are comprised mostly of silicate minerals Other distinctive properties: Mostly clay, may contain fossils Common depositional environment: Forms from compaction of fine particles that have been deposited in typically slow moving water