sedimentary
Sandstone with Ironstone Banding
Clastic Sandstone (composed of Quartz with Hematite/Limonite bonding)
Hardness: 6-7 on Mohs scale (quartz grains); Color: Tan, brown, and dark reddish-brown; Luster: Dull/Earthy; Structure: Clastic; Cleavage: None; Grain size: Medium.
- Hardness
- 6-7 on Mohs scale (quartz grains)
- Color
- Tan, brown, and dark reddish-brown
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 on Mohs scale (quartz grains); Color: Tan, brown, and dark reddish-brown; Luster: Dull/Earthy; Structure: Clastic; Cleavage: None; Grain size: Medium.
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains. The dark band is an ironstone layer formed by the precipitation of iron oxides (Limonite or Hematite) from groundwater passing through porous sediment. This specimen likely dates from the Paleozoic to Mesozoic era.
Uses & applications
Used primarily as decorative stone, landscape accents, and for geological study in teaching sedimentology.
Geological facts
The banding seen here, often called 'Liesegang rings' or bands, occurs when iron-rich fluids saturate the rock and rhythmic precipitation occurs due to chemical changes.
Field identification & locations
Identify in the field by its gritty texture and distinct color banding. Often found in dry riverbeds or eroded sedimentary basins across the American Southwest and UK.
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