sedimentary

Quartz pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale. Color: Light grey, translucent white to pale green. Luster: Vitreous to waxy. Crystal Structure: Hexagonal (microcrystalline/cryptocrystalline). Cleavage: None, exhibits conchoidal fracture. Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Light grey, translucent white to pale green
Luster: Vitreous to waxy

Identified July 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through mechanical weathering and stream erosion of silica-rich igneous, metamorphic, or sedimentary host rocks. Water action over extended periods smooths and rounds the rock into a pebble shape.

Uses & applications

Used in landscape gardening, decorative rockeries, aggregate in construction, stone tumbling for hobbyists, and high-purity quartz extraction for silicon electronics.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Rounded beach or river quartz pebbles can endure millions of years of water abrasion due to their hardness and chemical stability.

Field identification & locations

Identified by its scratch resistance (scratches glass easily, cannot be scratched by a steel pocketknife), translucent appearance, and smooth, water-worn texture. Commonly found in riverbeds, beaches, and glacial gravel deposits.