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Siltstone identification and geology

Siltstone rock reference specimen

Clastic sedimentary rock composed primarily of silt-sized particles 0.004-0.0625 mm . Intermediate between mudstone and sandstone. Texture: Fine-grained. Rock type: Sedimentary Clastic. Grain size: Silt 0.004-0.0625 mm. Minerals present: Quartz, Feldspar, Clay minerals, Mica. Formation: Forms from compaction of silt in moderate-energy environments like river floodplains and shallow marine settings. Common geological settings: Worldwide; found in fluvial, deltaic, and shallow marine sequences. Common look-alikes and related entries: Mudstone, Shale, Fine Sandstone.

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  • Previous: Shale — Fine-grained clastic sedimentary rock formed from compacted clay and silt. The most common sedimentary rock, showing fissility.
  • Next: Skarn — Coarse-grained metamorphic rock formed by metasomatic replacement at the contact between igneous intrusions and carbonate rocks.
  • Mudstone
  • Sandstone vs Siltstone — Compare observable properties and safer field tests.
  • Siltstone vs Shale — Compare observable properties and safer field tests.

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner
GeoMiner
Last updated
2026-03-30T14:38:19.462267+00:00
Review status
Published; not independently peer-reviewed
  • Rocks — U.S. National Park Service. Authoritative overview of rock groups, the rock cycle, and geologic processes.
  • Can you identify my rock or mineral? — U.S. Geological Survey. Identification limitations and routes to in-person professional verification.

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Common questions

What is Siltstone?
Clastic sedimentary rock composed primarily of silt-sized particles 0.004-0.0625 mm . Intermediate between mudstone and sandstone.
How can you identify Siltstone?
Compare several properties rather than relying on colour alone. This entry records rock type: Sedimentary Clastic; texture: Fine-grained; grain size: Silt 0.004-0.0625 mm; common minerals: Quartz, Feldspar, Clay minerals, Mica. Confirm an important identification with additional field tests or qualified laboratory work.
How does Siltstone form?
Forms from compaction of silt in moderate-energy environments like river floodplains and shallow marine settings.
Where is Siltstone commonly found?
Worldwide; found in fluvial, deltaic, and shallow marine sequences.
What is Siltstone commonly confused with?
Siltstone may be confused with Mudstone, Shale, Fine Sandstone. Compare multiple diagnostic properties because colour and surface appearance can overlap.

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