metamorphic
Quartzite Pebble
Metamorphosed Quartz Sandstone (SiO2)
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
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Physical properties
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
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
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