metamorphic
Quartzite Pebble
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: white/tan/off-white; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- white/tan/off-white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: white/tan/off-white; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from quartz-rich sandstone subjected to extreme heat and pressure during regional metamorphism, causing the quartz grains to recrystallize into a dense interlocking matrix.
Uses & applications
Used primarily as construction aggregate, railway ballast, crushed stone for road base, and decorative landscaping stone.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock, which is why it is frequently found as rounded river pebbles or coastal cobbles after millions of years of erosion.
Field identification & locations
Identify by its ability to scratch glass (hardness) and its sugary, crystalline texture. It is extremely common in riverbeds and glacial deposits worldwide.
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