sedimentary
Red Sandstone
Arenite (primarily SiO2 with Fe2O3)
Hardness: 6-7 Mohs; Color: reddish-brown to terracotta; Luster: dull/earthy; Crystal structure: granular clastic texture; Cleavage: none; Specific Gravity: 2.2-2.8
- Hardness
- 6-7 Mohs
- Color
- reddish-brown to terracotta
- Luster
- dull/earthy
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Physical properties
Hardness: 6-7 Mohs; Color: reddish-brown to terracotta; Luster: dull/earthy; Crystal structure: granular clastic texture; Cleavage: none; Specific Gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments, typically in desert or river delta environments. The red color indicates oxidation of iron-rich minerals (hematite) over millions of years.
Uses & applications
Commonly used as a building material, paving stone, decorative landscaping rock, and for making grindstones or sharpeners.
Geological facts
Red sandstone is famous for creating the iconic landscapes of the American Southwest, such as the Grand Canyon and Zion National Park. It is often referred to as 'Old Red Sandstone' in a historical geological context within Europe.
Field identification & locations
Identify in the field by its gritty, sandpaper-like feel and visible layered bedding (lamination). It is widely distributed across the globe in sedimentary basins; look for it in areas with exposed cliff faces or riverbeds.
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