sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale, typically white, clear, or light tan in color, vitreous to greasy luster, hexagonal crystal system when unweathered, conchoidal fracture with no true cleavage, specific gravity of 2.65.

Identified July 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the mechanical weathering and prolonged aqueous transportation of parent rocks (usually granite, pegmatite, or quartz veins) where softer minerals have eroded away, leaving behind durable quartz rounded into pebbles in rivers or beaches.

Uses & applications

Used in landscaping, decorative stone, manufacturing of glass and silicon, abrasives, and as a common specimen for beginner rock collectors.

Geological facts

Quartz is one of the most abundant and durable minerals in Earth's continental crust. Because of its extreme resistance to chemical weathering and high hardness, quartz pebbles can survive multiple cycles of erosion and redeposition over hundreds of millions of years.

Field identification & locations

Easily identified by its inability to be scratched by a steel knife (hardness > 5.5) and its smooth, water-worn shape. Found worldwide in stream beds, river gravels, and marine beaches.