sedimentary

Beach Pebble (Chert / Greywacke)

Silicon Dioxide (SiO2) / Quartz-rich Sandstone

AI-generated identification · may be incorrect

Hardness: 6.5-7 on Mohs scale. Color: Smooth greyish-brown with subtle quartz veinlets. Luster: Waxy to dull, glossy when wet. Structure: Fine-grained, massive. Conchoidal to uneven fracture.

Hardness: 6
Color: Smooth greyish-brown with subtle quartz veinlets
Luster: Waxy to dull, glossy when wet

Identified July 22, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 on Mohs scale. Color: Smooth greyish-brown with subtle quartz veinlets. Luster: Waxy to dull, glossy when wet. Structure: Fine-grained, massive. Conchoidal to uneven fracture.

Formation & geological history

Formed by the deposition and compaction of microcrystalline silica or fine mineral grains in marine or lacustrine environments. Smooth pebble morphology is produced by continuous natural water erosion and wave action along beaches or riverbeds.

Uses & applications

Commonly used for decorative landscaping, aquariums, polished stone crafts, and road construction aggregate.

Geological facts

Beach pebbles acquire their smooth, rounded shapes over decades or centuries of relentless erosion by ocean waves and river currents tumbling them against sand and other stones.

Field identification & locations

Look for rounded, water-worn stones with a smooth surface texture along ocean beaches, lakeshores, and riverbanks. These are extremely common worldwide.