Rocksday

Mudstone

Hardened mud that breaks into blocks rather than thin sheets.

Mudstone specimen
Photo: James St. John, CC BY 2.0, via Wikimedia Commons

How to identify mudstone

  • Smooth, very fine-grained.
  • Breaks into blocky chunks.
  • Soft; may smell earthy when wet.

Often confused with

Where it's found

  • Sedimentary basins worldwide
  • Gale crater, Mars

Uses

Brick and tile clay.

Rock tumbling

Not suitable for tumbling.

Did you know?

NASA's Curiosity rover drilled ancient lake mudstones in Mars' Gale crater.

Think you could spot it from a blurry close-up?

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