metamorphic

Quartzite Pebble

Quartzite (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 (Mohs), Color: Off-white/tan/cream, Luster: Dull to vitreous, Structure: Non-foliated granoblastic, Cleavage: None, Fracture: Conchoidal to splintery

Identified July 13, 2026More metamorphic →

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Physical properties

Hardness: 7 (Mohs), Color: Off-white/tan/cream, Luster: Dull to vitreous, Structure: Non-foliated granoblastic, Cleavage: None, Fracture: Conchoidal to splintery

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. This specimen shows a rounded shape due to alluvial or fluvial erosion (stream-worn).

Uses & applications

Used in construction as aggregate, railway ballast, as a decorative garden stone, and as a source of silica for manufacturing glass and ceramics.

Geological facts

Quartzite is so tough that it often outlasts the surrounding bedrock during erosion, resulting in smooth, rounded cobbles found far from their original source. It will scratch glass easily.

Field identification & locations

Identify in the field by its hardness (cannot be scratched by a steel blade) and its granular, sugary texture on a fresh break. Commonly found in riverbeds and glacial deposits.