metamorphic
Quartzite
Quartzite (chiefly SiO2)
Hardness: 7 on Mohs scale; Color: white, gray, or light tan; Luster: vitreous to dull; Crystal structure: trigonal (granular); Cleavage: none; Specific gravity: approx. 2.6
- Hardness
- 7 on Mohs scale
- Color
- white, gray, or light tan
- 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: white, gray, or light tan; Luster: vitreous to dull; Crystal structure: trigonal (granular); Cleavage: none; Specific gravity: approx. 2.6
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events (orogeny). It can range from Precambrian to Cenozoic in age.
Uses & applications
Used as crushed stone in road construction, as railway ballast, for decorative landscaping, and occasionally as a facing stone in architecture.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caprock or ridges of mountains, as it resists erosion much better than surrounding softer rocks.
Field identification & locations
Identify by its extreme hardness (it will scratch glass) and its sugary, granular appearance where individual quartz grains have fused together. Commonly found in metamorphic belts worldwide.
More like this
