mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Tan, beige, or milky white; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (though massive in this specimen); Cleavage: None (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on Mohs scale
Color: Tan, beige, or milky white
Luster: Vitreous to waxy

Identified July 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed from silica-rich hydrothermal fluids or crystallization of cooling magma. This particular specimen is a water-worn pebble, meaning it has been transported and smoothed by river or glacial action over thousands to millions of years.

Uses & applications

Used in construction as aggregate, in glassmaking, and in jewelry as semi-precious stones. High-purity quartz is also essential for electronics and oscillators.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to chemical and physical weathering, which is why it often survives as rounded pebbles like this long after other minerals have eroded into sand.

Field identification & locations

Identify in the field by its hardness (it should easily scratch glass) and lack of cleavage. Common in riverbeds, beaches, and gravel pits worldwide. Collectors often look for translucent or uniquely colored varieties.