mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs), Color: Tan to milky-gray, Luster: Waxy to vitreous, Crystal Structure: Trigonal (microcrystalline or massive in this form), Cleavage: None (conchoidal fracture), Specific Gravity: 2.65

Identified February 22, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily from hydrothermal solutions or as a byproduct of igneous cooling, this specific specimen has been chemically and mechanically weathered, likely rounded by water transport in a riverbed or stream. Age can range from millions to billions of years depending on location.

Uses & applications

Commonly used as construction aggregate, decorative landscaping stone, and in glass manufacturing or electronics when high purity. This weathered form is often used in rock tumblers.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. This specimen shows 'frosting' and pitting, which are typical signs of environmental abrasion over thousands of years.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (test for hardness 7) and its lack of cleavage planes. Found globally in stream beds, beaches, and glacial till. Collectors value unique water-worn shapes or 'river stones'.