metamorphic
Quartzite pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale. Color: Grayish-white with orange-red iron staining. Luster: Vitreous to waxy when wet. Structure: Granular, non-foliated. Cleavage: None. Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-white with orange-red iron staining
- Luster
- Vitreous to waxy when wet
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Physical properties
Hardness: 7 on Mohs scale. Color: Grayish-white with orange-red iron staining. Luster: Vitreous to waxy when wet. Structure: Granular, non-foliated. Cleavage: None. Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure in tectonic belts cause quartz grains to recrystallize. This specific specimen has been rounded by fluvial or glacial transport.
Uses & applications
Used as crushed stone for road construction, railroad ballast, and occasionally for high-durability countertops or decorative garden stones.
Geological facts
Quartzite is so tough that it often breaks through the internal quartz grains rather than around them. It is one of the most resistant rocks to chemical and physical weathering.
Field identification & locations
Identify by its ability to scratch glass and its granular, sugary texture. This specimen shows 'rutilated' or iron-oxide staining common in river-worn stones. Found worldwide in mountain ranges and glacial till.
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