metamorphic
Quartzite
Quartzite (Silicon Dioxide, SiO2)
Hardness: 7 on Mohs scale; Color: Off-white, greyish, translucent light yellow-brown; Luster: Vitreous to waxy/greasy; Crystal Structure: Trigonal (microcrystalline interlocked quartz grains); Cleavage: None (conchoidal to uneven fracture); Specific Gravity: ~2.65
- Hardness
- 7 on Mohs scale
- Color
- Off-white, greyish, translucent light yellow-brown
- Luster
- Vitreous to waxy/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: Off-white, greyish, translucent light yellow-brown; Luster: Vitreous to waxy/greasy; Crystal Structure: Trigonal (microcrystalline interlocked quartz grains); Cleavage: None (conchoidal to uneven fracture); Specific Gravity: ~2.65
Formation & geological history
Formed when quartz-rich sandstone undergoes heat, pressure, and chemical activity during regional metamorphism, fusing individual quartz grains tightly together. Found in various geological settings worldwide.
Uses & applications
Used as construction aggregate, crushed stone, railway ballast, decorative landscaping stone, countertops, and historically for stone tools.
Geological facts
Quartzite is so hard and tough that when it breaks, the fracture cuts through the individual quartz grains rather than along the boundaries between them, unlike sandstone.
Field identification & locations
Identify in the field by its extreme hardness (scratches glass and steel), lack of reaction to acid, and grainy yet vitreous fused texture. Commonly found in stream beds, glacial deposits, and mountainous metamorphic terrains.
More like this
