sedimentary

Sandstone (Ferruginous)

Arenite with Iron Oxide cement

AI-generated identification · may be incorrect

Hardness: 6-7 on Mohs scale; Color: Reddish-brown, tan, or rusty due to iron oxidation; Luster: Dull or earthy; Crystal structure: Granular (clastic texture); Cleavage: None; Specific gravity: 2.2 - 2.8

Hardness: 6-7 on Mohs scale
Color: Reddish-brown, tan, or rusty due to iron oxidation
Luster: Dull or earthy

Identified June 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains or rock fragments. The reddish hue indicates an oxygen-rich environment during deposition or later weathering where iron minerals like hematite or goethite acted as the cementing agent. Most common in terrestrial or shallow marine environments.

Uses & applications

Used primarily as construction material, paving stone, road aggregate, and historically for building monuments. Fine-grained variants are sometimes used for sharpening tools (whetstones).

Geological facts

Sandstone contains about 20-25% of all sedimentary rocks in the Earth's crust. It is a major reservoir for groundwater, oil, and natural gas due to its porosity and permeability. The Grand Canyon's famous red layers are largely composed of various ferruginous sandstones.

Field identification & locations

Identify in the field by its 'sandpaper' feel when rubbed. It should leave a gritty residue. Often found in layered outcrops, riverbeds, and deserts. Collectors look for unique banding or fossil inclusions.