sedimentary

Sandstone (with Iron Staining)

Clastic sedimentary rock (primarily SiO2 with Fe2O3 staining)

Hardness: 6-7 on Mohs scale (quartz-based); Color: Tan, bluff, or grey with reddish-brown streaks; Luster: Dull/Earthy; Crystal structure: Clastic (granular texture); Cleavage: None; Specific gravity: 2.2-2.8

Hardness: 6-7 on Mohs scale (quartz-based)
Color: Tan, bluff, or grey with reddish-brown streaks
Luster: Dull/Earthy

Identified May 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the accumulation and cementation of sand-sized mineral grains or rock fragments, typically in river beds, deserts, or marine environments. The reddish banding is caused by the oxidation of iron minerals (hematite/goethite) within the groundwater.

Uses & applications

Commonly used as a building material, paving stone, and in the production of glass. It is also used as a reservoir rock in the petroleum industry.

Geological facts

Sandstone can preserve fossilized footprints and ripple marks from ancient water currents. The red coloring, often called 'Liesegang rings,' occurs when minerals precipitate from groundwater in beautiful banded patterns.

Field identification & locations

Identify in the field by its gritty 'sandpaper' feel and visible grain layers. It is ubiquitous in arid regions and canyon landscapes like the American Southwest.

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