Quartzite Pebble

Physical Properties

Hardness: 7 (Mohs scale); Color: Snowy white to light pink/tan; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7

Formation & Geological History

Formed through the metamorphism of quartz-rich sandstone. Under intense heat and pressure, individual quartz grains recrystallize into a dense interlocking mosaic. Often smoothed into rounded shapes by fluvial (river) or glacial transport.

Uses & Applications

Used as decorative landscaping stones, road ballast, and as a raw material for glass making or metallurgical processes when high purity silica is present.

Geological Facts

Quartzite is so hard that it will scratch glass and steel easily. It is one of the most durable rocks on the Earth's surface, often remaining as 'islands' of resistant rock in landscapes that have otherwise eroded away.

Field Identification & Locations

Identify by its hardness (cannot be scratched by a knife) and its grainy, 'sugary' texture upon a fresh break. Commonly found in riverbeds, glacial tills, and ancient mountain belts.

Identified on: 4/19/2026

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