metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 (Mohs); Color: Tan, brownish-orange, and grey; Luster: Vitreous to waxy (when wet/polished); Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture).
- Hardness
- 7 (Mohs)
- Color
- Tan, brownish-orange, and grey
- Luster
- Vitreous to waxy (when wet/polished)
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Physical properties
Hardness: 7 (Mohs); Color: Tan, brownish-orange, and grey; Luster: Vitreous to waxy (when wet/polished); Structure: Granular, non-foliated; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. This specimen appears river-worn or water-tumbled.
Uses & applications
Used in construction as road ballast, in glass manufacturing (if high purity), and popular for tumbling or as decorative garden stones.
Geological facts
Quartzite is so tough that it often outlasts the original surrounding rock during erosion, which is why it is frequently found as rounded river stones like this one.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife) and its grainy, crystalline texture that resembles sugar. Commonly found in riverbeds and glacial deposits.
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