sedimentary

Shale / Mudstone

Laminated Mudrock (Siliciclastic Sedimentary Rock)

Hardness: 3-4 on Mohs scale; Color: Dark grey to blackish brown; Luster: Dull, earthy; Crystal Structure: Microcrystalline/Aphanitic, composed mainly of fine clay minerals and quartz grains; Cleavage: Fissile, splits easily along thin laminae; Specific Gravity: ~2.4-2.8.

Hardness: 3-4 on Mohs scale
Color: Dark grey to blackish brown
Luster: Dull, earthy

Identified July 26, 2026More sedimentary →

Explore Shale / Mudstone in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed through the compaction and lithification of silt and clay-sized mineral particles deposited in low-energy environments such as river deltas, lakes, deep marine basins, and floodplains.

Uses & applications

Widely used in the manufacturing of brick, tile, and Portland cement. Hydrocarbon-rich shales serve as important source rocks for natural gas and petroleum.

Geological facts

Shale is the most abundant sedimentary rock on Earth, making up over half of the entire sedimentary rock record. It frequently contains well-preserved microfossils.

Field identification & locations

Identified in the field by its fine-grained earthy appearance, dark coloration, softness relative to steel, and characteristic tendency to split into thin sheets (fissility). Common globally in sedimentary basins.

Other sedimentary specimens

See all

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

Sedimentary Shale

sedimentary

Shale and Pebble Fragment

Sedimentary Rock (Mudstone/Shale with Silica Pebble)

sedimentary