mineral

Quartz (River Pebble)

Silicon Dioxide (SiO₂)

Hardness: 7 on the Mohs scale; Color: Tan to off-white, translucent; Luster: Vitreous to waxy (when water-worn); Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture).

Hardness: 7 on the Mohs scale
Color: Tan to off-white, translucent
Luster: Vitreous to waxy (when water-worn)

Identified March 21, 2026More mineral →

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Physical properties

Hardness: 7 on the Mohs scale; Color: Tan to off-white, translucent; Luster: Vitreous to waxy (when water-worn); Crystal Structure: Trigonal/Hexagonal; Cleavage: None (conchoidal fracture).

Formation & geological history

Formed through the cooling of silica-rich magma or precipitation from hydrothermal veins. This specific specimen is a water-worn river pebble, shaped by alluvial erosion over thousands of years.

Uses & applications

Industrial uses include glassmaking, abrasives, and electronics (as oscillators). Smooth pebbles are frequently used in landscaping, aquariums, and decorative stone mulch.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. These rounded shapes are caused by 'saltation,' where rocks tumble against each other in riverbeds, smoothing out the crystal faces.

Field identification & locations

Identify in the field by its hardness (it will scratch glass) and lack of cleavage. Found globally in riverbeds, beaches, and glacial till. Collectors look for translucent clarity or unique patterns.