sedimentary

River Stone (River Pebble)

Stream-rounded clast (likely Quartzite or Siltstone)

Hardness: 6-7 (if quartz-based); Color: Grayish-green to brownish-tan; Luster: Dull/Earthy; Crystal structure: Cryptocrystalline; Cleavage: None; Shape: Well-rounded and smooth due to fluvial abrasion.

Hardness: 6-7 (if quartz-based)
Color: Grayish-green to brownish-tan
Luster: Dull/Earthy

Identified May 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the mechanical weathering and transport of rock fragments in high-energy water environments like rivers or streams. The smooth, rounded shape is a result of years of 'saltation' where rocks knock against each other in water currents.

Uses & applications

Commonly used in landscaping, decorative ground cover, aquarium substrates, and as aggregate in concrete construction. High-quality smooth stones are also used for massage therapy and rock painting.

Geological facts

River stones are geological time travelers; the rounded shape can tell geologists about the intensity and distance of water flow that moved the rock from its parent outcrop. Some river pebbles can be millions of years old.

Field identification & locations

Identified by its exceptionally smooth, rounded surface and lack of sharp edges. Commonly found in riverbeds, glacial deposits, and coastal beaches. Collectors should look for unique banding or internal patterns when the stone is wet.

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