sedimentary

Red sandstone

Quartz-rich clastic sandstone, commonly iron-oxide cemented (SiO₂ with Fe₂O₃/FeOOH)

AI-generated identification · may be incorrect

Typically Mohs 6–7 for quartz grains, reddish-brown, dull to earthy luster, porous, and composed of visible sand-sized particles; bedding or lamination may occur. Exact composition cannot be confirmed from the photo alone.

Identified September 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when deposited sand is compacted and cemented, with iron oxides producing the red color; ages range from Precambrian to recent, depending on locality. Common in rivers, deserts, beaches, and ancient dune or floodplain deposits.

Uses & applications

Used as building and paving stone, aggregate, architectural stone, and occasionally as a decorative specimen. The pictured fragment has modest collector value.

Geological facts

Its red coloration usually indicates oxidation in an oxygen-rich depositional or groundwater environment. Fresh breaks commonly reveal gritty texture and individual quartz grains.

Field identification & locations

Identify by its granular, gritty fracture, layered texture, and reaction-free behavior with dilute hydrochloric acid; it is softer and more porous than quartzite. Common worldwide, especially in red-bed formations such as the Colorado Plateau and New Red Sandstone regions.