metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on the Mohs scale; Color: typically white to gray, can be yellowish or pink; Luster: vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: approx. 2.65.
- Hardness
- 7 on the Mohs scale
- Color
- typically white to gray, can be yellowish or pink
- 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 the Mohs scale; Color: typically white to gray, can be yellowish or pink; Luster: vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Specific gravity: approx. 2.65.
Formation & geological history
Formed from the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, creating an extremely durable rock.
Uses & applications
Used in construction as road ballast, gravel, and dimension stone. High-purity quartzite is used to produce ferrosilicon, industrial silica sand, and silicon metal.
Geological facts
Quartzite is so tough that it often breaks through the quartz grains rather than around them, which is a key way to distinguish it from sandstone. It is resistant to chemical weathering.
Field identification & locations
Identify in the field by its sugary texture and extreme hardness (it will easily scratch glass). It lacks the visible bedding planes found in its parent rock, sandstone. Found globally in ancient mountain belts.
