metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Grayish-tan to white; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Grayish-tan to white
- 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: Grayish-tan to white; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: None/Conchoidal fracture; Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together into a dense, interlocking structure.
Uses & applications
Used extensively in road construction (crushed stone), as railway ballast, for decorative tile, and as a raw material for glass manufacturing and silicon production.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the crests of mountain ridges through differential weathering. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify in the field by its hardness (7) and 'sugary' texture. Unlike sandstone, when broken, quartzite fractures through the grains rather than around them. Found globally in ancient mountain belts.
More like this
