mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 on Mohs scale; Color: Milky white to off-white/tan; Luster: Vitreous (glassy) to waxy when weathered; Crystal Structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 on Mohs scale
Color: Milky white to off-white/tan
Luster: Vitreous (glassy) to waxy when weathered

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the cooling of silica-rich magma or from hydrothermal veins. This specific specimen has been chemically weathered and physically rounded through fluvial (river) or glacial transport, resulting in its smooth, sub-spherical shape.

Uses & applications

Industrial use as an abrasive, in glassmaking, and in electronics (piezoelectric properties). In this pebble form, it is commonly used for landscaping, decorative gravel, and construction aggregate.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. White 'milky' quartz gets its color from tiny fluid inclusions of gas or liquid trapped during crystal growth.

Field identification & locations

Identify in the field by its hardness (it will scratch glass and stainless steel) and its lack of cleavage. These rounded pebbles are commonly found in stream beds, beaches, and glacial till deposits worldwide.