sedimentary

Sandstone (River Pebble)

Clastic Sedimentary Rock (primarily Quartzite/Arenite)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Tan, brown, or buff with visible bedding planes; Luster: Dull/Earthy; Structure: Fine-grained clastic; Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 Mohs
Color: Tan, brown, or buff with visible bedding planes
Luster: Dull/Earthy

Identified July 6, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: Tan, brown, or buff with visible bedding planes; Luster: Dull/Earthy; Structure: Fine-grained clastic; Cleavage: None; Specific Gravity: 2.2-2.8

Formation & geological history

Formed from the accumulation and cementation of sand-sized mineral particles or rock fragments. The rounded shape indicates significant water erosion, likely from a riverbed or stream environment, occurring over thousands to millions of years.

Uses & applications

Common river pebbles are used for decorative landscaping, aquarium substrate, and as aggregate in construction and concrete. Larger sandstone deposits provide building stone.

Geological facts

Sandstone contains a record of the past, often preserving ripple marks, cross-bedding, and occasionally fossils that indicate the flow direction of prehistoric rivers or winds of ancient deserts.

Field identification & locations

Identify by its gritty texture (feels like sandpaper) and visible layering (stratification). Found globally in riverbeds, beaches, and sedimentary basins. Collectors often look for unique erosion patterns or 'lucky' smooth shapes.