sedimentary
Ferruginous Sandstone
Arenite with Iron-Oxide Cement (SiO2 with Fe2O3/FeO(OH))
Hardness: 6-7 (Mohs); Color: Tan, brown, reddish-orange; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.5-3.0
- Hardness
- 6-7 (Mohs)
- Color
- Tan, brown, reddish-orange
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 (Mohs); Color: Tan, brown, reddish-orange; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None; Specific Gravity: 2.5-3.0
Formation & geological history
Formed through the lithification of sand-sized grains (mostly quartz) cemented together by iron oxides like hematite or limonite. It typically forms in river, desert, or marine environments where iron-rich groundwater can circulate.
Uses & applications
Used primarily in construction as a building stone or road aggregate. Some high-iron varieties are crushed for industrial iron pigment or flux in glassmaking.
Geological facts
The red and brown 'desert' landscapes often owe their color to the iron-oxide staining found in sandstones like this. It is one of the most common rocks found in terrestrial sedimentary basins.
Field identification & locations
Identify in the field by its sandy texture (feeling like sandpaper) and its distinctive rusty staining. It is commonly found in river beds, canyon walls, and exposed ridges in sedimentary regions.
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