metamorphic
Quartzite
SiO2 (Silicon Dioxide)
AI-generated identification · may be incorrectHardness: 7 on Mohs scale; Color: Tan, white, or light brownish; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Tan, white, or light brownish
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Tan, white, or light brownish; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize and fuse together, typically in mountain-building environments.
Uses & applications
Used as crushed stone for road construction, railway ballast, and as a decorative stone in landscaping. High-purity quartzite is used to produce ferrosilicon and silicon metal.
Geological facts
Quartzite is so tough that it often remains as caps on hills or ridges because it is much more resistant to weathering and erosion than the surrounding rocks.
Field identification & locations
Identify by its ability to scratch glass and its grainy, sandpaper-like surface that lacks the distinct layering of sandstone. Look for it in river beds or glacial till. It will not react with acid.
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