metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or grayish-blue as shown; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none; Specific gravity: approx 2.65.
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or grayish-blue as shown
- 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 on Mohs scale; Color: typically white, gray, or grayish-blue as shown; Luster: vitreous to dull; Crystal structure: hexagonal (microcrystalline); Cleavage: none; Specific gravity: approx 2.65.
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, creating a dense, hard rock. Often found in mountainous or Precambrian shield regions.
Uses & applications
Used extensively in construction as road ballast, gravel, and dimension stone for tiles/flooring. High-purity quartzite is used in industry to produce silicon for glass and electronics.
Geological facts
Quartzite is so tough that it often fractures across the original grains rather than around them. It is one of the most weather-resistant rocks on the Earth's surface.
Field identification & locations
Identify in the field by its grainy, sugary texture and extreme hardness (it will easily scratch glass). Look for it in areas with folded mountain belts. It is common in riverbeds as smooth, rounded cobbles due to its durability.
More like this
