sedimentary

Quartz Pebble

Crystalline Silica (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on Mohs scale; Color: Brownish-gray, translucent to opaque; Luster: Dull to waxy when unpolished; Crystal Structure: Trigonal (often worn away in pebbles); Cleavage: None/Conchoidal fracture.

Hardness: 7 on Mohs scale
Color: Brownish-gray, translucent to opaque
Luster: Dull to waxy when unpolished

Identified July 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed via crystallization from silica-rich fluids or erosion of metamorphic/igneous veins. This specific specimen has been rounded by fluvial processes (water erosion) in a riverbed or coastal environment.

Uses & applications

Used as decorative landscaping stones, aquarium gravel, or crushed for industrial silica glass production.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. River-worn pebbles like this can travel hundreds of miles from their original source, becoming increasingly rounded over time.

Field identification & locations

Identify by its inability to be scratched by a steel knife and its lack of visible grains (unlike sandstone). Commonly found in riverbeds, beaches, and glacial till.