mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to translucent grey; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to translucent grey
Luster: Vitreous to waxy

Identified March 21, 2026More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Milky white to translucent grey; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed through hydrothermal processes or within igneous rocks (granite). This specimen has been smoothed and rounded by long-term water erosion in a fluvial (river) or coastal environment.

Uses & applications

Common quartz is used in construction as aggregate, in glass manufacturing, and as abrasive material. Smooth pebbles are popular for landscaping, aquarium decor, and stone tumbling.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its name comes from the German word 'quarz', which has Slavic origins. It is piezoelectric, meaning it generates an electric charge in response to mechanical stress.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife and its lack of cleavage. It is found globally in riverbeds, beaches, and soil. Collectors look for clarity or unique inclusions.