mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on the Mohs scale; Color: Milky white to translucent with yellowish staining; Luster: Vitreous (glassy) to waxy; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on the Mohs scale
Color: Milky white to translucent with yellowish staining
Luster: Vitreous (glassy) to waxy

Identified March 15, 2026More mineral →

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Physical properties

Formation & geological history

Formed from cooling silica-rich magma or precipitation in hydrothermal veins. This specific specimen is a 'clat' or river pebble, meaning it has been weathered and rounded by water transport over hundreds to thousands of years after eroding from a primary vein.

Uses & applications

Used in glass manufacturing, electronics (due to piezoelectric properties), construction aggregates, and as a semi-precious gemstone in jewelry when found in high clarity.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. It is highly resistant to both chemical and physical weathering, which is why it often survives as rounded pebbles in riverbeds while other minerals break down into clay.

Field identification & locations

Identify in the field by its inability to be scratched by a steel knife (7 hardness) and its lack of cleavage. It is commonly found in riverbeds, beaches, and soil. To collectors, the smooth 'water-worn' texture is a key aesthetic feature.