metamorphic
Quartzite pebble
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale. Color: light gray to off-white with a matte to dull surface. Luster: dull to vitreous on fresh breaks. Granular, interlocking quartz crystal structure.
- Hardness
- 7 on Mohs scale
- Color
- light gray to off-white with a matte to dull surface
- Luster
- dull to vitreous on fresh breaks
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale. Color: light gray to off-white with a matte to dull surface. Luster: dull to vitreous on fresh breaks. Granular, interlocking quartz crystal structure.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone, where heat and pressure recrystallize quartz grains into a dense, hard interlocking network.
Uses & applications
Commonly used as construction aggregate, railway ballast, landscaping gravel, and decorative river rocks.
Geological facts
Quartzite is so tough and resistant to weathering that rounded quartzite pebbles often survive multiple cycles of erosion and redeposition over hundreds of millions of years.
Field identification & locations
Identified by its high hardness (scratches glass easily) and granular surface that breaks across quartz grains rather than around them. Found globally along riverbeds, beaches, and glacial deposits.
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