sedimentary
Claystone / Mudstone
Mudstone (Hydrous aluminum silicate rich rock)
Hardness: 1-2.5 Mohs. Color: Earthy brown to tan and reddish-brown. Luster: Dull, earthy. Structure: Fine-grained, non-cleavage, earthy fracture. Specific Gravity: 2.0-2.6.
- Hardness
- 1-2
- Color
- Earthy brown to tan and reddish-brown
- Luster
- Dull, earthy
Identified More sedimentary →
Explore Claystone / Mudstone in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 1-2.5 Mohs. Color: Earthy brown to tan and reddish-brown. Luster: Dull, earthy. Structure: Fine-grained, non-cleavage, earthy fracture. Specific Gravity: 2.0-2.6.
Formation & geological history
Formed by the compaction and lithification of fine-grained mud, clay, and silt particles deposited in calm water environments such as lakes, river floodplains, or shallow marine basins.
Uses & applications
Used in the manufacturing of bricks, ceramics, and cement, or as fill material in construction. Has limited value to collectors unless it contains fossils.
Geological facts
Mudstones make up over half of the sedimentary rocks in the Earth's crust. When subjected to higher heat and pressure over time, mudstone metamorphoses into slate.
Field identification & locations
Identify by its soft, earthy texture, fine-grained appearance, and tendency to feel smooth or sticky when moistened. Commonly found in riverbeds, lakeshores, and sedimentary basins worldwide.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale
Argillaceous sedimentary rock
sedimentary
Mudstone
Argillite / Siliciclastic sedimentary rock
sedimentary