metamorphic
Quartzite
Quartzite (Metamorphic Quartz Sandstone)
Hardness: 7 on Mohs scale. Color: Tan, brown, white, or gray. Luster: Vitreous to greasy. Crystal structure: Trigonal (microcrystalline interlocking quartz grains). Cleavage: None (fractures conchoidally). Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Tan, brown, white, or gray
- Luster
- Vitreous to greasy
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: Tan, brown, white, or gray. Luster: Vitreous to greasy. Crystal structure: Trigonal (microcrystalline interlocking quartz grains). Cleavage: None (fractures conchoidally). Specific gravity: 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically in mountain-building belts over hundreds of millions of years.
Uses & applications
Used in construction, as crushed stone for roads, for railway ballast, in manufacturing refractory bricks, and occasionally as decorative stone or countertops.
Geological facts
Unlike sandstone, which breaks around the individual sand grains, quartzite breaks straight through the grains because the quartz cement has fused so tightly with the original sand particles.
Field identification & locations
Extremely resistant to weathering and chemical attack. Found worldwide in ancient mountain roots and sedimentary basins. Identify by its sugary texture on broken surfaces, extreme hardness (scratches glass easily), and lack of reaction to acid.
More like this
