metamorphic
Quartzite Pebble
Metamorphic Quartzite (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale); Color: Tan, beige, white, or yellowish; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific gravity: 2.63–2.65
- Hardness
- 7 (Mohs scale)
- Color
- Tan, beige, white, or yellowish
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Tan, beige, white, or yellowish; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific gravity: 2.63–2.65
Formation & geological history
Formed through the metamorphism of sandstone under intense heat and pressure. This specimen shows water-worn rounding, likely from a riverbed or coastal environment.
Uses & applications
Commonly used in construction as aggregate, road ballast, or decorative landscaping stone. In a high-purity state, it can be a source of silica for glassmaking.
Geological facts
Quartzite is so tough that it often outlasts other surrounding rocks during erosion, remaining as rounded pebbles in stream beds for millions of years. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by a steel knife) and granular, sugary texture. It is extremely common in glacial till and riverbeds across North America and Europe.
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