Mineral

Quartz (specifically a water-worn river pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent tan to smoky white; Luster: Vitreous (glassy) to waxy; Crystal Structure: Hexagonal (though obscured by weathering); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65.

Hardness: 7 on Mohs scale
Color: Translucent tan to smoky white
Luster: Vitreous (glassy) to waxy

Identified March 30, 2026More mineral →

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Physical properties

Formation & geological history

Formed from cooling magma or hydrothermal veins. This specific specimen has been chemically weathered and physically abraded by water transport in a river or alluvial environment, likely dating from the Phanerozoic eon depending on the local bedrock.

Uses & applications

Used primarily in glassmaking, abrasives, and electronics (as piezoelectric crystals). Smooth pebbles are often used in landscaping, aquariums, or as industrial 'grinding media'.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its name comes from the German word 'quarz', which originally meant 'hard'. Because of its chemical stability, it is the primary component of most 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. Typically found in riverbeds, glacial tills, and mountain wash. This specimen is an 'indicator' mineral for more complex geological formations upstream.

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