sedimentary

River Pebble (likely Quartzite or Siltstone)

Sedimentary Clast (SiO2 based)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs); Color: Tan, brown, and grey with iron staining; Luster: Dull/Earthy; Structure: Clastic/Granular; Cleavage: None.

Hardness: 6-7 (Mohs)
Color: Tan, brown, and grey with iron staining
Luster: Dull/Earthy

Identified June 28, 2026More sedimentary →

Explore River Pebble (likely Quartzite or Siltstone) in the encyclopedia →

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Physical properties

Hardness: 6-7 (Mohs); Color: Tan, brown, and grey with iron staining; Luster: Dull/Earthy; Structure: Clastic/Granular; Cleavage: None.

Formation & geological history

Formed through the erosion and weathering of larger rock formations, subsequently transported and rounded by water action in a river or stream environment. Its age can range from thousands to millions of years depending on the parent rock source.

Uses & applications

Primarily used in landscaping, construction aggregate, aquarium decor, and as a tactile object for hobbyist collectors.

Geological facts

The smooth, rounded shape is a result of 'attritional wear,' where rocks collide with each other in moving water, wearing down sharp edges over time. Small pebbles like this are key indicators of past water flow in geological surveys.

Field identification & locations

Identify by its smooth, water-worn texture and rounded edges. Common in riverbeds, glacial deposits, and beaches. Collectors often use them for rock tumbling or as base materials for painted rock art.