sedimentary
Ferruginous Sandstone
Ferruginous Sandstone (Quartz grains with Iron Oxide cement)
Hardness: 6-7 (individual grains); Color: Red, brown, or rusty-orange due to iron oxidation; Luster: Dull/Earthy; Structure: Clastic, medium-grained; Cleavage: None (granular)
- Hardness
- 6-7 (individual grains)
- Color
- Red, brown, or rusty-orange due to iron oxidation
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (individual grains); Color: Red, brown, or rusty-orange due to iron oxidation; Luster: Dull/Earthy; Structure: Clastic, medium-grained; Cleavage: None (granular)
Formation & geological history
Formed through the accumulation and cementation of sand-sized grains, typically quartz, where iron-rich groundwater or fluids precipitate hematite or limonite as a mineral cement between the grains. Common in terrestrial or shallow marine environments.
Uses & applications
Used primarily as building stone in local construction, decorative landscaping, and occasionally as a low-grade iron ore if iron content is extremely high.
Geological facts
The distinct reddish-brown color is caused by the same oxidation process that creates rust. This stone is a major component of famous formations like the 'Red Rocks' of the American Southwest.
Field identification & locations
Identify in the field by its gritty 'sandpaper' texture and the staining of fingers with a reddish residue when rubbed. It is often found in stratigraphic layers within canyon walls or riverbeds.
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