sedimentary

Sandstone (Quartz-rich Cobble)

Arenite

Hardness: 6-7 (Mohs); Color: Tan, gray, or buff with orange iron oxidation spots; Luster: Dull/Earthy; Texture: Granular/Sand-like feel; Cleavage: None

Hardness: 6-7 (Mohs)
Color: Tan, gray, or buff with orange iron oxidation spots
Luster: Dull/Earthy

Identified July 18, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs); Color: Tan, gray, or buff with orange iron oxidation spots; Luster: Dull/Earthy; Texture: Granular/Sand-like feel; Cleavage: None

Formation & geological history

Formed through the accumulation and cementation of sand-sized mineral grains, typically quartz and feldspar, in high-energy environments like rivers, beaches, or deserts. This specimen shows a rounded shape indicative of fluvial or glacial transport.

Uses & applications

Used widely in construction for building stone, paving, and as an abrasive. Crushed sandstone is used to make glass and for industrial sand-casting.

Geological facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The orange spots on this specimen are likely iron oxide (limonite or hematite) leached from internal minerals or environmental water.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and visible grains. It is extremely common in riverbeds, canyons, and mountainous regions worldwide. It often preserves fossils and ripple marks from ancient environments.