metamorphic
Quartzite Pebble
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Off-white to light gray with slight tan staining; Luster: Vitreous to dull when weathered; Structure: Granular/crystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Off-white to light gray with slight tan staining
- Luster
- Vitreous to dull when weathered
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Physical properties
Hardness: 7 on Mohs scale; Color: Off-white to light gray with slight tan staining; Luster: Vitreous to dull when weathered; Structure: Granular/crystalline; Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone under intense heat and pressure. The specimen shown is a water-worn river pebble, likely transported and rounded over thousands to millions of years.
Uses & applications
Used as a decorative garden stone, in landscaping, as a construction aggregate, and historically as a material for stone tools due to its hardness.
Geological facts
Quartzite is so tough that it can cut through glass and is much harder than most steel blades. Unlike sandstone, quartzite breaks through its individual grains rather than around them.
Field identification & locations
Identify in the field by its hardness (will scratch glass) and its sugary, crystalline appearance on a fresh break. Most common in riverbeds, glacial deposits, and mountain ranges.
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