sedimentary

Sandstone (Ferruginous)

Arenite with Iron Oxide staining (Fe2O3)

AI-generated identification · may be incorrect

Hardness: 6-7 on Mohs scale; Color: Tan, brown, reddish-orange due to iron oxidation; Luster: Dull, earthy; Crystal structure: Clastic (composed of sand-sized grains); Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 on Mohs scale
Color: Tan, brown, reddish-orange due to iron oxidation
Luster: Dull, earthy

Identified May 24, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral particles or rock fragments, typically in riverbeds, deserts, or coastal environments. This specific specimen shows signs of water-rounding, suggesting it was tumbled in a river or beach environment.

Uses & applications

Used widely in construction such as building stones, paving, and flagging. It is also an important reservoir rock for groundwater and petroleum.

Geological facts

Sandstone accounts for roughly 20-25% of all sedimentary rocks on Earth. The red and brown colors are often caused by the presence of iron oxide minerals like hematite or goethite acting as a cement or coating on the grains.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and visible sand grains. These water-worn cobbles are commonly found in glacial till, river deposits, and along coastlines.