metamorphic
Quartzite
Quartzite (high SiO2 content)
Hardness: 7 on Mohs scale; Color: typically white, gray, or reddish/purple due to iron oxides; Luster: vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: none.
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or reddish/purple due to iron oxides
- 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: typically white, gray, or reddish/purple due to iron oxides; Luster: vitreous to dull; Crystal structure: Non-foliated, granular; Cleavage: none.
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, typically in orogenic belts. This specific specimen appears to be a water-worn river cobble.
Uses & applications
Used as crushed stone for road construction, railroad ballast, tile, and decorative stone in landscaping. High-purity quartzite is used in glassmaking.
Geological facts
Quartzite is so tough that it often fractures through the quartz grains rather than along the boundaries between them, unlike sandstone. The orange spots on this specimen are crustose lichens living on the surface.
Field identification & locations
Identify in the field by its extreme hardness (it will easily scratch glass) and its sugary, crystalline surface. It is commonly found in ancient mountain ranges and glacial deposits.
More like this
