sedimentary

Earthy Siltstone with Iron Staining

Siltstone / Argillite with Goethite/Hematite inclusions

Hardness: 3-5 (variable); Color: Tan, brown, and grey with reddish-brown oxidation; Luster: Dull/Earthy; Crystal structure: Clastic (microscopic grain size); Cleavage: None (conchoidal to irregular fracture)

Hardness: 3-5 (variable)
Color: Tan, brown, and grey with reddish-brown oxidation
Luster: Dull/Earthy

Identified July 14, 2026More sedimentary →

Explore Earthy Siltstone with Iron Staining in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed by the compaction and lithification of silt-sized particles often deposited in low-energy environments like river floodplains or lake beds. The reddish-brown layers indicate oxidation of iron minerals within the sedimentary layers.

Uses & applications

Commonly used as fill material in construction or as a source of aggregate. In some cases, siltstones with high clay content are used for making bricks or tiles.

Geological facts

Siltstone is intermediate between sandstone and shale. If the grains are too small to be seen but can be felt as 'gritty' against the teeth, it is classified as siltstone rather than claystone.

Field identification & locations

Identified in the field by its fine-grained texture that is grittier than shale but smoother than sandstone. It often displays thin laminations. Found in sedimentary basins worldwide.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Brown Sandstone (River Rock)

Arenite

sedimentary

Mudstone

Argillite / Siliciclastic sedimentary rock

sedimentary

Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

sedimentary

Sandstone

Arenite (primarily SiO2)

sedimentary

Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

sedimentary