sedimentary

Mudstone

Lutylite (group of fine-grained sedimentary rocks)

AI-generated identification · may be incorrect

Hardness: 2-3 (Mohs scale), Color: Dark grey, charcoal to brown, Luster: Dull/Earthy, Crystal Structure: Microcrystalline, Cleavage: None (it has no fissility, unlike shale), Specific Gravity: 2.4 - 2.8

Identified March 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the lithification of suspended particles of silt and clay. These materials typically settle in low-energy environments like lake bottoms, deep oceans, or flood plains. They can range in age from modern deposits to billions of years old.

Uses & applications

Used primarily in the construction industry as fill material or as a raw material for brick, cement, and pottery. Occasionally used for building foundations where it is stable.

Geological facts

Mudstone is one of the most common sedimentary rocks on Earth, covering roughly 65% of all sedimentary rock distributions. Unlike shale, it does not split into thin layers.

Field identification & locations

Identify in the field by its fineness (the grains are too small to see with the naked eye) and its lack of fine layering. It will feel gritty when rubbed against the teeth and usually breaks into blocky chunks. Commonly found in riverbeds and ancient coastal basins.