Rock Identifier
Quartz Pebble (Silicon Dioxide (SiO2)) — mineral
mineral

Quartz Pebble

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Translucent tan to milky white; Luster: Vitreous to waxy (when water-worn); Crystal Structure: Hexagonal (though rounded by erosion); Cleavage: None, conchoidal fracture.

Hardness
7 on Mohs scale
Color
Translucent tan to milky white
Luster
Vitreous to waxy (when water-worn)
Identified More mineral →

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Physical properties

Hardness: 7 on Mohs scale; Color: Translucent tan to milky white; Luster: Vitreous to waxy (when water-worn); Crystal Structure: Hexagonal (though rounded by erosion); Cleavage: None, conchoidal fracture.

Formation & geological history

Formed in igneous or metamorphic veins before being weathered out and transported by water. This specific specimen shows rounding typical of alluvial (river) or coastal erosion during the Holocene or older periods.

Uses & applications

Used in construction as aggregate, in glass manufacturing, and as decorative gravel. Transparent specimens are used in jewelry as semi-precious stones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its high hardness and lack of cleavage make it incredibly resistant to mechanical weathering, which is why it often remains as pebbles while other minerals turn to silt.

Field identification & locations

Identify by its inability to be scratched by a steel knife and its lack of cleavage planes. Common in riverbeds, beaches, and glacial till globally.

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