mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Milky white to pale grey. Luster: Vitreous to waxy (water-worn). Crystal structure: Trigonal (microcrystalline/massive). Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Milky white to pale grey
Luster: Vitreous to waxy (water-worn)

Identified July 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich magma or precipitation from hydrothermal fluids, then exposed, eroded, and rounded by water transport in rivers, streams, or coastal environments.

Uses & applications

Commonly used in landscaping, river rock aggregate, glassmaking, electronics (piezoelectric applications), and as a basic specimen for lapidary tumbling or rock collecting.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Rounded white quartz pebbles are often referred to as 'river stones' or 'milky quartz pebbles'.

Field identification & locations

Identified in the field by its hardness (scratches glass, cannot be scratched by a steel knife), lack of cleavage, milky translucency, and smooth, water-worn exterior. Found abundantly in riverbeds, beaches, and glacial deposits worldwide.