metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: white, grey, or yellowish; Luster: vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- white, grey, or yellowish
- Luster
- vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: white, grey, or yellowish; Luster: vitreous to dull; Crystal structure: Trigonal/Hexagonal (microcrystalline); Cleavage: none (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, causing the original quartz grains to recrystallize into an interlocking mosaic.
Uses & applications
Used in construction as crushed stone for road beds, in the glass industry as a source of silica, and as decorative stone for landscaping or countertops.
Geological facts
Quartzite is so tough that it often survives intense erosion to form the tops of ridges and mountains. It is harder than steel and will easily scratch glass.
Field identification & locations
Identifiable by its sugary texture and extreme hardness (cannot be scratched by a knife). Commonly found in ancient mountain belts and riverbeds where it has been smoothed by water travel.
