metamorphic
Quartzite
Quartzite (principally SiO2)
Hardness: 7 on Mohs scale; Color: white to light gray; Luster: vitreous to dull; Crystal structure: granular, interlocking grains of quartz; Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- white to light gray
- 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 to light gray; Luster: vitreous to dull; Crystal structure: granular, interlocking grains of quartz; Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7.
Formation & geological history
Formed from the regional metamorphism of quartz-rich sandstone. Under intense heat and pressure, the individual quartz grains recrystallize and fuse together into a dense, hard metamorphic rock.
Uses & applications
Used in construction as crushed stone for road grit and railway ballast, as a decorative stone in architecture (countertops and flooring), and historically as a material for stone tools.
Geological facts
Quartzite is so tough that it often outlasts surrounding rocks during weathering, frequently forming the caps of ridges and mountains. It is one of the hardest and most durable common rocks.
Field identification & locations
Identify by its extreme hardness (it will easily scratch glass) and lack of reaction to acid. It often appears sugary or grainy but is very smooth to the touch. Commonly found in folded mountain belts globally.
