metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Reddish-brown to pink due to iron oxide impurities; Luster: Vitreous to dull; Crystal structure: Granular, interlocking quartz grains; Cleavage: None, breaks with conchoidal or irregular fracture.
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown to pink due to iron oxide impurities
- Luster
- Vitreous to dull
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-brown to pink due to iron oxide impurities; Luster: Vitreous to dull; Crystal structure: Granular, interlocking quartz grains; Cleavage: None, breaks with conchoidal or irregular fracture.
Formation & geological history
Quartzite is formed when quartz-rich sandstone is subjected to intense heat and pressure during regional metamorphism, causing the sand grains to recrystallize and fuse together. It can range from Precambrian to much younger geological ages.
Uses & applications
Used extensively as crushed stone for road construction, railroad ballast, and decorative landscaping. High-purity quartzite is used to produce silicon, ferrosilicon, and silicon carbide.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, forming prominent ridges and peaks. It is often confused with marble, but quartzite will scratch glass and will not fizz in acid.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by a steel nail) and its granular appearance where individual sand grains are barely visible because they have fused. Common in mountain belts globally.
More like this
