metamorphic
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
Hardness: 7 on Mohs scale; Color: White to light grey; Luster: Vitreous to dull; Crystal structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- White to light grey
- 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 Mohs scale; Color: White to light grey; Luster: Vitreous to dull; Crystal structure: Hexagonal (trigonal); Cleavage: Indistinct/Conchoidal fracture; Specific gravity: 2.6-2.7.
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, causing the original quartz grains to recrystallize and fuse together. Often found in orogenic belts.
Uses & applications
Used as crushed stone for road construction, railway ballast, and as a decorative stone in architecture and landscaping. High-purity quartzite is used in glass making.
Geological facts
Quartzite is so hard and dense that when a rock hammer hits it, it often produces a spark. Unlike sandstone, when quartzite breaks, it breaks through the quartz grains rather than around them.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Commonly found in mountainous regions or as river-worn cobbles.
More like this
