metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: White with pinkish and gray streaks; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- White with pinkish and gray streaks
- 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: White with pinkish and gray streaks; Luster: Vitreous to dull; Crystal structure: Trigonal; Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, typically during tectonic mountain-building events. The individual quartz grains recrystallize into a locked mosaic of crystals.
Uses & applications
Used in construction for road ballast, roofing granules, and as a decorative stone in landscaping. High-purity quartzite is used to produce glass and metallic silicon.
Geological facts
Quartzite is so durable that it often remains as ridges or peaks when surrounding softer rocks have eroded away. It is tougher than the sandstone from which it originated.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. It is commonly found in ancient mountain ranges and glacial deposits.
More like this
