metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: white to light gray with yellowish iron staining; Luster: vitreous to dull; Crystal structure: trigonal (granular texture); Cleavage: none; Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- white to light gray with yellowish iron staining
- 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 to light gray with yellowish iron staining; Luster: vitreous to dull; Crystal structure: trigonal (granular texture); Cleavage: none; Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during regional mountain-building events. The original quartz sand grains recrystallize into a dense interlaced structure.
Uses & applications
Used in construction for road ballast, roofing granules, and as a dimension stone. High-purity quartzite is used to produce ferrosilicon, industrial silica sand, and silicon metal.
Geological facts
Quartzite is so tough that it often survives intense weathering better than most other rocks, frequently forming the caps of ridges and mountain peaks. It is often harder than the steel of a pocket knife.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by steel) and its crystalline, sugary texture. Unlike sandstone, it breaks through the quartz grains rather than around them. Found globally in ancient mountain belts.
More like this
