Skip to main content


Mudstone is a fine-grained, generally dark grey sedimentary rock formed from deposits of silt and clay. Unlike shale, mudstone tends to have no laminations. Small outcrops of mudstone of various ages occur across Northern Ireland and may be seen as random blocks of rubble stone along with other stone types. In Omagh mudstone has been used as a building stone on several buildings and is likely to be mudstone associated with the Carboniferous Omagh or Claragh Sandstone Groups.