sedimentary

River Pebbles (Chert and Quartzite)

Sedimentary Clastic Rock (Silica-rich)

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: tan, brown, grey, cream, and reddish-orange; Luster: matte to waxy; Structure: microcrystalline or granular; Shape: rounded to sub-rounded due to water erosion.

Hardness: 6
Color: tan, brown, grey, cream, and reddish-orange
Luster: matte to waxy

Identified July 14, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 (Mohs scale); Color: tan, brown, grey, cream, and reddish-orange; Luster: matte to waxy; Structure: microcrystalline or granular; Shape: rounded to sub-rounded due to water erosion.

Formation & geological history

Formed through the weathering and erosion of larger rock masses, transported by rivers and streams. These specific specimens are primarily made of microcrystalline quartz (chert) or metamorphosed sandstone (quartzite) that has been tumbled by water over thousands of years.

Uses & applications

Commonly used in landscaping, aquarium decor, drainage systems, decorative pathways, and as a raw material for construction aggregates.

Geological facts

The rounded shape is a direct result of 'abrasion' during transport in water. Geologists use the roundness of these pebbles to determine how far the sediment has traveled from its source.

Field identification & locations

Identify by their smooth, rounded surface and high hardness (most will scratch glass). They are found globally in riverbeds, beaches, and glacial deposits. Look for a 'waxy' texture upon close inspection of chert pieces.