metamorphic
Red Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Reddish-brown/pink; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown/pink
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-brown/pink; Luster: Vitreous to dull; Crystal structure: Trigonal (granular texture); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, typically during mountain-building events (orogeny). The red color comes from iron oxide impurities.
Uses & applications
Used in construction as crushed stone for road gravel, as decorative landscaping stone, and occasionally as a refractory material in glass making.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the ridges of mountain ranges because it weathers much more slowly than surrounding rocks.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of visible individual sand grains compared to sandstone. Commonly found in shield areas like the Appalachians or the Canadian Shield.
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