mudstone

American  

[muhd-stohn] / ˈmʌdˌstoʊn /

noun

Geology.

1. a clayey rock with the texture and composition of shale but little or no lamination.

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mudstone British  

/ ˈmʌdˌstəʊn /

noun

1. a dark grey clay rock similar to shale but with the lamination less well developed

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mudstone Scientific  

/ mŭd′stōn′ /

1. A fine-grained, dark gray sedimentary rock consisting primarily of compacted and hardened silt and clay, similar to shale but without laminations. The proportions of silt and clay in mudstone are approximately equal.

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Etymology

Origin of mudstone

First recorded in 1730–40; mud + stone

Compare meaning

How does mudstone compare to similar and commonly confused words? Explore the most common comparisons:

• mudstone vs. shale

Example Sentences

Spotted in July 2024, the reddish mudstone contains organic compounds and other minerals that could have supported bygone microbial Martians.

From The Wall Street Journal • Apr. 23, 2026

Known as North America's most fertile source of dinosaur fossils, it contains massive deposits of mudstone, sandstone, and limestone from ancient rivers and floodplains.

From Science Daily • Feb. 1, 2026

They are about 3.5bn years old and are a type of rock called mudstone, which is fine-grained rock formed from clays.

From BBC • Sep. 10, 2025

The name she picked aligns with other rock types, like sandstone, mudstone, and limestone.

From Slate • Apr. 27, 2024

Bed 5, compact, fine-grained, pale greenish-grey, non- calcareous, indurated mudstone, easily fusible into a pale green and white glass.

From Geological Observations on South America by Darwin, Charles