metamorphic
Quartzite Pebble
Metamorphic Quartzite (predominantly SiO2)
Hardness: 7 (Mohs scale); Color: Grayish-white with yellow-brown iron staining and dark mineral inclusions; Luster: Dull to waxy; Structure: Non-foliated, granular; Specific Gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Luster
- Dull to waxy
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Physical properties
Hardness: 7 (Mohs scale); Color: Grayish-white with yellow-brown iron staining and dark mineral inclusions; Luster: Dull to waxy; Structure: Non-foliated, granular; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen has been further shaped and smoothed by water transport (fluvial or glacial activity).
Uses & applications
Commonly used as construction aggregate, road ballast, and decorative landscaping stones. Smooth pebbles are frequently used in home decor and aquariums.
Geological facts
Quartzite is so durable that it often outlasts the mountain ranges from which it originated, ending up as rounded river stones millions of years later. It is harder than steel and will scratch glass easily.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife) and granular, sugary appearance when broken. Widely found in riverbeds, glacial tills, and beaches globally.
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