sedimentary
Ferruginous Sandstone
Ferruginous Sandstone (Quartz Arenite with Iron Oxide cement)
Hardness: 6-7 (individual grains); Color: Reddish-brown, rusty orange; Luster: Dull to earthy; Structure: Granular/Clastic texture; Specific gravity: 2.6-3.0
- Hardness
- 6-7 (individual grains)
- Color
- Reddish-brown, rusty orange
- Luster
- Dull to earthy
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Physical properties
Hardness: 6-7 (individual grains); Color: Reddish-brown, rusty orange; Luster: Dull to earthy; Structure: Granular/Clastic texture; Specific gravity: 2.6-3.0
Formation & geological history
Formed through the deposition and lithification of sand-sized quartz grains, where iron-rich groundwater precipitates minerals like hematite or limonite as a cementing agent between the grains.
Uses & applications
Commonly used as a building stone, in landscaping, and sometimes as a low-grade iron ore in historical contexts.
Geological facts
The intense red or brown color is often referred to as 'desert varnish' when found on surfaces in arid environments. This rock is responsible for the famous red landscapes of the American Southwest.
Field identification & locations
Identified by its sandy, gritty texture and the fact that its reddish-brown staining will not wash off. Found globally in ancient riverbeds and desert environments.
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