metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: White, gray, or pale pink; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- White, gray, or pale pink
- Luster
- Vitreous to dull
Identified More metamorphic →
Explore Quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 (Mohs scale); Color: White, gray, or pale pink; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: None; 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 (orogenic processes). The quartz grains recrystallize into a dense, interlocking mosaic.
Uses & applications
Used as crushed stone for road construction, railway ballast, and as a raw material for decorative crushed stone. High-purity quartzite is used to produce glass and silicon metal.
Geological facts
Quartzite is so tough that it often survives erosion better than the rocks around it, creating prominent ridges or hills. It can be distinguished from marble because it will not fizz with acid and is hard enough to scratch glass.
Field identification & locations
Identify by its sugary, granular appearance and extreme hardness. It won't be scratched by a steel knife. Commonly found in folded mountain belts worldwide.
More like this
