sedimentary
Ferruginous Sandstone
Ferruginous Clastic Sedimentary Rock
Hardness: 6-7 (Mohs scale); Color: Brown, reddish-brown, or rusty orange; Luster: Dull or earthy; Crystal structure: Granular/clastic; Cleavage: None; Specific gravity: 2.6-3.0.
- Hardness
- 6-7 (Mohs scale)
- Color
- Brown, reddish-brown, or rusty orange
- Luster
- Dull or earthy
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Physical properties
Hardness: 6-7 (Mohs scale); Color: Brown, reddish-brown, or rusty orange; Luster: Dull or earthy; Crystal structure: Granular/clastic; Cleavage: None; Specific gravity: 2.6-3.0.
Formation & geological history
Formed by the accumulation of sand-sized grains (mostly quartz) that are cemented together by iron oxides like hematite or goethite. This process typically occurs in riverbeds, lakes, or marine environments over millions of years.
Uses & applications
Used primarily in construction as a building material, paving stones, and sometimes as an abrasive in industrial processes. Higher quality pieces are used for landscaping or decorative rock garden features.
Geological facts
The red or brown color is a result of the oxidation of iron minerals, similar to the process of rusting. It is a major component of famous geological landmarks like the Red Rocks in Colorado and the Grand Canyon.
Field identification & locations
Identify in the field by its gritty, sandpaper-like texture and its tendency to leave a reddish streak if scratched. It is commonly found in sedimentary basins and areas with high iron content in the groundwater.
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