metamorphic

Quartzite Pebble

Quartzite (Metamorphosed Quartz Sandstone, SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on the Mohs scale; Color: Tan, brown, reddish-brown, or light gray; Luster: Vitreous to greasy on fresh surfaces, matte when weathered; Crystal structure: Interlocking quartz grains (microcrystalline to crystalline); Cleavage: None, breaks with a conchoidal fracture; Specific Gravity: 2.65 - 2.75

Hardness: 7 on the Mohs scale
Color: Tan, brown, reddish-brown, or light gray
Luster: Vitreous to greasy on fresh surfaces, matte when weathered

Identified August 5, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone or chert under high tectonic heat and pressure, typically in mountain-building events over millions of years. This specific specimen has been smoothed and rounded into a pebble by wave action in a beach or river environment.

Uses & applications

Used in landscaping, decorative stone, construction aggregate, and occasionally as a tumbling or lapidary specimen.

Geological facts

Quartzite is extremely durable and resistant to chemical weathering, which is why quartz-rich rocks often survive long journeys in riverbeds and shorelines long after other rock types have eroded away.

Field identification & locations

Can be identified in the field by its extreme hardness (will easily scratch glass and cannot be scratched by a steel knife) and the sugary texture of interlocking quartz grains visible on broken surfaces. Commonly found in riverbeds, glacial tills, and beaches worldwide.