sedimentary

River Pebbles (White Quartz and Basalt mix)

Mixed Clastic Sedimentary Assemblage (SiO2 and Mafic Volcanics)

AI-generated identification · may be incorrect

Hardness: 6-7 (Quartz), 5-6 (Basalt). Color: White, black, brown. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline to fine-grained. Cleavage: Indistinct. Specific gravity: 2.6-3.0.

Hardness: 6-7 (Quartz), 5-6 (Basalt)
Color: White, black, brown
Luster: Dull to vitreous

Identified June 23, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Quartz), 5-6 (Basalt). Color: White, black, brown. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline to fine-grained. Cleavage: Indistinct. Specific gravity: 2.6-3.0.

Formation & geological history

Formed through the mechanical weathering and water transportation of larger rock formations. Over time, river action smooths the edges into rounded shapes through abrasion. Common in riverbeds and coastal areas.

Uses & applications

Used primarily for landscaping, decorative garden beds, aquarium substrate, and as aggregates in concrete or architectural finishes.

Geological facts

The rounded shape is a direct result of 'rounding,' a geological process where particles collide during transport in water, removing sharp edges.

Field identification & locations

Identify by the smooth, rounded 'egg-like' shape. White stones are typically quartz; darker stones are usually basalt or chert. Found globally in alluvial deposits.