Quartz (River Pebble)

Physical Properties

Hardness: 7 (Mohs scale), Color: White/Off-white/Milky, Luster: Vitreous to waxy, Crystal Structure: Trigonal/Hexagonal, Cleavage: None (conchoidal fracture), Specific gravity: 2.65

Formation & Geological History

Formed through the cooling of silica-rich magma or from hydrothermal veins. This specific specimen has been shaped and smoothed through mechanical weathering and erosion in a river or coastal environment.

Uses & Applications

Used widely in manufacturing glass, electronics, abrasives, and as a component in construction concrete. Polished pebbles are used in landscaping and interior decor.

Geological Facts

Quartz is the second most abundant mineral in Earth's continental crust. When found in riverbeds, its rounded shape is a record of miles of travel and years of tumbling against other stones.

Field Identification & Locations

Identify in the field by its hardness (it can scratch glass and cannot be scratched by a steel knife) and the absence of cleavage. Found globally in riverbeds, beaches, and glacial deposits.

Identified on: 4/25/2026

Mode: Standard