mineral

Quartz pebble

Silicon Dioxide (SiO2)

Hardness: 7 Mohs scale; Color: Clear to milky white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 Mohs scale
Color: Clear to milky white
Luster: Vitreous to waxy

Identified May 23, 2026More mineral →

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Physical properties

Hardness: 7 Mohs scale; Color: Clear to milky white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Formation & geological history

Formed from silica-rich fluids in hydrothermal veins or as a primary constituent of igneous rocks. This specific specimen is a water-worn river pebble, shaped by mechanical erosion over thousands of years in a high-energy fluvial environment.

Uses & applications

Commonly used in landscaping as decorative river rock, in construction aggregates, and as a source for high-purity silica for glassmaking and electronics. Tumbled specimens are popular with beginner rock collectors.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Most sand on beaches is composed almost entirely of small, weathered quartz grains like this one because of its high chemical and physical resistance.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (7 hardness) and its lack of cleavage. It is commonly found in stream beds, river banks, and glacier deposits globally.