Quartzite Pebble

Physical Properties

Hardness: 7 (Mohs scale); Color: Tan, beige, or yellowish due to iron oxides; Luster: Vitreous to dull; Crystal structure: Hexagonal; Cleavage: Indistinct/conchoidal fracture; Specific gravity: approx 2.65

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize into a dense rock. This specific specimen has been rounded by water erosion (alluvial action).

Uses & Applications

Used widely in construction as crushed stone, for landscaping (river rocks), and as a raw material for glass manufacturing. Smooth pebbles are popular for decorative gardens and aquariums.

Geological Facts

Quartzite is harder than steel; if you try to scratch glass with it, it will leave a mark. It is one of the most durable rocks on Earth, often surviving long after surrounding softer rocks have eroded away.

Field Identification & Locations

Identify in the field by its hardness and granular texture that breaks through the grains rather than around them. Commonly found in riverbeds, glacial deposits, and mountain ranges.

Identified on: 4/20/2026

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