sedimentary
Red Sandstone
Arenite (predominantly SiO2 with Fe2O3 staining)
Hardness: 6-7 Mohs; Color: Brownish-red or reddish-pink; Luster: Dull/Earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 Mohs
- Color
- Brownish-red or reddish-pink
- Luster
- Dull/Earthy
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Physical properties
Hardness: 6-7 Mohs; Color: Brownish-red or reddish-pink; Luster: Dull/Earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of mineral particles or rock fragments (sand) in desert or river environments. Red coloration indicates iron oxide (hematite) staining from oxygen-rich environments. Common in the Colorado Plateau and ancient rift valleys.
Uses & applications
Used widely as a building material, paving stone, and in decorative landscaping. Historically significant in the construction of 'brownstone' rowhouses.
Geological facts
Red sandstone formations like those in Sedona or the Grand Canyon represent millions of years of wind-blown dunes and river deposits. The red color is essentially 'rust' on the surface of individual quartz grains.
Field identification & locations
Identify by its gritty texture (feels like sandpaper) and visible layering or bedding. Look for it in arid regions or where ancient riverbeds have been uplifted. It won't react with acid unlike limestone.
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