metamorphic
Quartzite River Rock
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Grey, brown, and tan with bands; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Grey, brown, and tan with bands
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Grey, brown, and tan with bands; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure. The specimen shown is a well-rounded pebble, likely shaped by long-term fluvial (river) erosion.
Uses & applications
Used primarily in construction as crushed stone or gravel, as road ballast, and occasionally as decorative landscaping stones.
Geological facts
Quartzite is one of the most durable and weather-resistant rocks on Earth. It often forms prominent ridges because it resists erosion much better than the surrounding rock types.
Field identification & locations
Can be identified in the field by its inability to be scratched by steel and its grainy, sandpaper-like texture that sparkles slightly under light. Commonly found in riverbeds and glacial deposits.
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