Quartzite (River Pebble)

Physical Properties

Hardness: 7 (Mohs scale); Color: White to off-white with minor iron staining; Luster: Vitreous/waxy when wet, dull when dry; Crystal Structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture).

Formation & Geological History

Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. This specific specimen has been rounded and smoothed by fluvial (river) or glacial transport processes.

Uses & Applications

Used in landscaping (decorative stone), construction aggregate, and as a raw material for glass and ceramics in larger quantities.

Geological Facts

Quartzite is so hard and chemically resistant that it often forms the capstone of mountains. It is harder than steel and will easily scratch glass.

Field Identification & Locations

Identify by its hardness (cannot be scratched by a steel knife) and its grainy, sugary texture when broken. Commonly found in riverbeds and glacial tills across North America and Europe.

Identified on: 4/19/2026

Mode: Standard