mineral

Quartz (River Pebble)

Silicon Dioxide (SiO2)

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

Hardness: 7 on Mohs scale
Color: Milky white to tan
Luster: Vitreous to waxy (when polished)

Identified March 27, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed through the cooling of silica-rich magma or from hydrothermal veins. The rounded shape indicates secondary transport in a high-energy aquatic environment, such as a river or beach, where it was tumbled and smoothed over thousands of years.

Uses & applications

Used universally in construction (sand/aggregate), glass making, electronics (oscillators), and as an abrasive. Smooth river stones are popular for landscaping, zen gardens, and massage therapy.

Geological facts

Quartz is the second most abundant mineral in Earth's continental crust. Its name comes from the German word 'Quarz', and it has been used since prehistoric times to make stone tools through flintknapping.

Field identification & locations

Identify by its ability to scratch glass and lack of cleavage. Look for 'frosting' or tiny crescent-shaped impact fractures on the surface, typical of water-worn quartz. Found globally in almost every riverbed and beach.