mineral

Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on the Mohs scale. Color: Tan, beige, or milky white. Luster: Vitreous (glassy) to waxy when weathered. Crystal structure: Trigonal/Hexagonal. Cleavage: None (conchoidal fracture). Specific gravity: 2.65.

Hardness: 7 on the Mohs scale
Color: Tan, beige, or milky white
Luster: Vitreous (glassy) to waxy when weathered

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids or within igneous and metamorphic rocks. This specific specimen is a 'clast' that has been rounded by fluvial (river) or marine (beach) erosion over thousands of years.

Uses & applications

Quartz is used in glassmaking, electronics (piezoelectric properties), abrasives, and as a component in concrete. Tumbled pebbles like this are often used in decorative landscaping and aquarium gravel.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Over time, these pebbles break down further to become the primary component of beach sand.

Field identification & locations

Identify in the field by its hardness (it will easily scratch glass but cannot be scratched by a steel knife) and lack of cleavage. Found globally in riverbanks, beaches, and glacial till. For collectors, look for smoothness and translucency.