mineral

Quartz (Water-worn Pebble)

Silicon Dioxide (SiO2)

Hardness: 7 (Mohs scale); Color: Milky white to translucent off-white; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.65

Hardness: 7 (Mohs scale)
Color: Milky white to translucent off-white
Luster: Vitreous to waxy

Identified June 28, 2026More mineral →

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Physical properties

Hardness: 7 (Mohs scale); Color: Milky white to translucent off-white; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal; Cleavage: None (Conchoidal fracture); Specific Gravity: 2.65

Formation & geological history

Formed from silica-rich hydrothermal solutions or cooling magma. This specific specimen is a 'river rock' or 'tumble' that has been eroded and smoothed by mechanical weathering in a waterway or coastal environment over thousands of years.

Uses & applications

Used widely in glassmaking, electronics (piezoelectric properties), abrasives, and as decorative gravel or gemstones.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Pure quartz is clear, but tiny inclusions of gas or liquid trapped during crystal growth create the 'milky' appearance seen here.

Field identification & locations

Identify by its hardness (it will scratch glass) and lack of cleavage. It is found globally in riverbeds, beaches, and soil. For collectors, it is a basic staple of any local rock collection.