sedimentary

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness of 7 on the Mohs scale; white, translucent, or light yellowish-brown color due to iron staining; vitreous to greasy luster; trigonal crystal system when formed as crystals, but amorphous as a rounded pebble; conchoidal fracture; no true cleavage; specific gravity of 2.65.

Identified July 31, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from parent igneous, metamorphic, or hydrothermal quartz veins that weathered and eroded over long periods. The loose quartz fragments were transported by water in rivers or wave action along coasts, where mechanical abrasion rounded them into smooth pebbles over thousands to millions of years.

Uses & applications

Used in landscaping, decorative stone, aquarium gravel, abrasive manufacturing, and occasionally in lapidary work for cabochons.

Geological facts

Quartz is one of the most abundant and durable minerals in Earth's continental crust. Its high resistance to both chemical weathering and physical abrasion is why quartz pebbles survive long journeys in riverbeds and beaches long after other minerals have broken down into clay.

Field identification & locations

Identified in the field by its smooth water-worn shape, high hardness (will easily scratch glass and steel), lack of effervescence with acid, and vitreous luster. Commonly found in river gravel bars, alluvial deposits, and ancient conglomerate formations worldwide.