metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: Tan, orange-brown, or reddish due to iron staining; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: None; Specific gravity: 2.6-2.7
- Hardness
- 7 (Mohs scale)
- Color
- Tan, orange-brown, or reddish due to iron staining
- 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 (Mohs scale); Color: Tan, orange-brown, or reddish due to iron staining; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular texture); Cleavage: None; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure. This specimen displays water-worn smoothing, suggesting it was transport by a river or glacial activity.
Uses & applications
Used in construction as crushed stone or decorative landscaping. High-purity quartzite is used in glass manufacturing and as a source of silica in metallurgy.
Geological facts
Quartzite is so tough that it often survives the weathering process better than the surrounding rocks, often forming the caps of hills or ridges. It is harder than steel, meaning it will scratch a knife blade.
Field identification & locations
Identify by its grainy, sugary texture and extreme hardness. Look for a conchoidal fracture if broken. It is a common find in glacial till across North America and mountainous regions globally.
More like this
