metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Gray, white, or light tan; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Specific gravity: approx. 2.6
- Hardness
- 7 on Mohs scale
- Color
- Gray, white, or light tan
- 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: Gray, white, or light tan; Luster: Vitreous to dull; Crystal structure: Non-foliated, granular; Specific gravity: approx. 2.6
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together, creating a very dense and durable rock.
Uses & applications
Used extensively in construction as road ballast, railway track ballast, flooring, roofing tiles, and as a decorative stone in landscaping. High-purity quartzite is used to produce silica sand for glassmaking.
Geological facts
Quartzite is so hard and tough that it will break through the quartz grains rather than around them (unlike sandstone). It is often more resistant to weathering than the surrounding rock, frequently forming ridges and hilltops.
Field identification & locations
Identify in the field by its hardness (it will easily scratch glass) and its sugary, crystalline texture that lacks the distinct foliation layers found in rocks like slate or gneiss. Commonly found in folded mountain ranges.
More like this
