sedimentary
Red Sandstone
Arenite (primarily Quartz with Iron Oxide coating)
Hardness: 6-7 (Mohs scale), Color: Red to reddish-brown, Luster: Dull/Earthy, Crystal Structure: Granular/Clastic, Cleavage: None, Specific Gravity: 2.2 - 2.8
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Red to reddish-brown, Luster: Dull/Earthy, Crystal Structure: Granular/Clastic, Cleavage: None, Specific Gravity: 2.2 - 2.8
Formation & geological history
Formed through the accumulation of sand-sized mineral grains, primarily quartz, which are then cemented together by minerals like silica, calcium carbonate, or iron oxide (hematite) which provides the red color. Typically formed in arid desert or river floodplain environments.
Uses & applications
Widely used as a building material, decorative stone in masonry, flagging for pathways, and as an abrasive in some industrial processes.
Geological facts
Red sandstone is responsible for many of the iconic landscapes in the American Southwest, such as the Grand Canyon and Zion National Park. It has been used in historic architecture worldwide, including the Red Fort in India and many brownstone buildings in New York City.
Field identification & locations
Identify in the field by its gritty texture (feels like sandpaper) and visible layering or cross-bedding. It will not fizz with acid unless it has a calcitic cement. Found globally in basins and desert regions.
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