metamorphic
Quartzite Pebble
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Tan, brown, or light yellow; Luster: Vitreous to waxy (especially when water-worn); Crystal structure: Hexagonal (microcrystalline); Cleavage: None/Conchoidal fracture.
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, or light yellow
- Luster
- Vitreous to waxy (especially when water-worn)
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, brown, or light yellow; Luster: Vitreous to waxy (especially when water-worn); Crystal structure: Hexagonal (microcrystalline); Cleavage: None/Conchoidal fracture.
Formation & geological history
Formed through the regional or contact metamorphism of quartz sandstone. The high pressure and temperature cause the sand grains to recrystallize and fuse together.
Uses & applications
Used as decorative landscaping stones, aggregate in construction, or for lapidary work (tumbling and polishing).
Geological facts
Quartzite is so tough that it often survives intense mechanical weathering, which is why it is commonly found as smooth, rounded pebbles on beaches or in riverbeds long after softer rocks have eroded.
Field identification & locations
Identify in the field by its inability to be scratched by a steel knife and its grainy, crystalline texture. It is ubiquitous in glaciated regions and along high-energy coastlines.
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