sedimentary

Sandstone (Ferruginous)

Arenite (Fe2O3 staining)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs scale; Color: Rusty brown, orange, tan; Luster: Dull or earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8

Hardness: 6-7 Mohs scale
Color: Rusty brown, orange, tan
Luster: Dull or earthy

Identified March 21, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs scale; Color: Rusty brown, orange, tan; Luster: Dull or 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 sand-sized mineral particles or rock fragments. The distinct orange-brown color is caused by the oxidation of iron-rich mineral cement during the lithification process, most common in terrestrial riverine or desert environments.

Uses & applications

Used primarily in building construction as a dimension stone, as an abrasive material, and as an aquifer and reservoir for groundwater and petroleum in industry.

Geological facts

Sandstone makes up approximately 20-25% of all sedimentary rocks on Earth. The rusted appearance is known as 'desert varnish' when found on the surface of outcrop walls in arid regions.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and visible layering or bedding planes. It is found globally in riverbeds, canyons, and sedimentary basins. Collectors look for unique concretions or fossil inclusions within the matrix.