sedimentary

Red sandstone fragment

Ferruginous sandstone, chiefly quartz (SiO₂) with iron-oxide cement

AI-generated identification · may be incorrect

Typically Mohs hardness 6–7 for quartz grains; reddish-brown, dull to slightly gritty, with visible granular texture and layered bedding. Quartz is trigonal and lacks cleavage; the specimen appears irregularly fractured and moderately porous.

Identified August 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when sand, mainly quartz, is compacted and cemented by silica, calcite, or iron oxides; the red color reflects oxidized iron. Its exact age and formation basin cannot be determined from the photograph.

Uses & applications

Used as building and paving stone, aggregate, and decorative stone; attractive pieces may be collected but usually have modest value.

Geological facts

Iron-rich sandstone is commonly called red sandstone and can preserve ripple marks, cross-bedding, or fossils. The rusty coloration is analogous to terrestrial “rust” produced during weathering and cementation.

Field identification & locations

Look for sand-sized grains, stratification, gritty texture, and red coloration; a glass scratch test may help confirm abundant quartz. Common worldwide, especially in arid continental basins and coastal formations.