mudstone

American  

[muhd-stohn] / ˈmʌdˌstoʊn /

noun

Geology.

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

---

mudstone British  

/ ˈmʌdˌstəʊn /

noun

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

---

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.

---

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

See Examples For:

mudstone

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

The rock that contained these compounds is an ancient mudstone located in Gale Crater.

From Science Daily ● Feb. 12, 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 specimen, which Dr. Glasspool discovered in a mudstone from southern Wales, is one of many pieces of ancient charcoal that have been studied in recent years to explore how fires burned in the past.

From New York Times ● May 10, 2024

On this there are two strata of the pale brown mudstone, also like that of S. Josef, separated by a darker-coloured, more argillaceous variety, including the Ostrea Patagonica.

From Geological Observations on South America by Darwin, Charles