metamorphic

Quartzite Pebble

Metamorphosed Quartz Sandstone (SiO2)

AI-generated identification · may be incorrect

Hardness: 7 on the Mohs scale; Color: Light gray, tan, or white with a granular texture; Luster: Vitreous to dull; Crystal structure: Interlocking quartz crystals; Cleavage: None, breaks across grains (conchoidal fracture); Specific gravity: 2.65

Hardness: 7 on the Mohs scale
Color: Light gray, tan, or white with a granular texture
Luster: Vitreous to dull

Identified August 1, 2026More metamorphic →

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Physical properties

Formation & geological history

Formed through the metamorphism of quartz-rich sandstone under high heat and pressure, commonly in tectonic mountain-building events over millions of years

Uses & applications

Used in landscaping, decorative stone, construction aggregate, and occasionally in the manufacture of silica brick and glass

Geological facts

Quartzite is extremely durable and resistant to chemical weathering, which is why quartz-rich rocks often survive as smooth, rounded pebbles in riverbeds and beaches long after other rocks have eroded away

Field identification & locations

Can be identified in the field by its high hardness (scratches glass easily), lack of reaction to acid, and sugary, interlocking crystalline fracture surface; commonly found in river gravels, glacial drift, and mountainous regions worldwide