metamorphic
Quartzite Pebble
Quartzite
Hardness: 7 on the Mohs scale. Color: Generally gray, white, or light brownish. Luster: Vitreous to greasy. Crystal structure: Non-foliated, interlocking quartz crystals. Cleavage: None, fractures conchoidally. Specific gravity: 2.65.
- Hardness
- 7 on the Mohs scale
- Color
- Generally gray, white, or light brownish
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale. Color: Generally gray, white, or light brownish. Luster: Vitreous to greasy. Crystal structure: Non-foliated, interlocking quartz crystals. Cleavage: None, fractures conchoidally. Specific gravity: 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through regional or contact metamorphism, subjecting the parent rock to high temperatures and pressures over millions of years.
Uses & applications
Used in construction, as crushed stone for roadbeds, railway ballast, and in the manufacturing of refractory bricks and silica blocks.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why it often survives as rounded pebbles in riverbeds and beaches long after other rocks have eroded away.
Field identification & locations
Found worldwide in mountainous regions and riverbeds. It can be identified by its high hardness (scratches glass easily) and the sugary texture of interlocking quartz grains visible under magnification.
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