metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Typically white to gray, can be pink or reddish due to iron oxide; Luster: Vitreous to greasy; Crystal structure: Trigonal (microcrystalline interlocking quartz grains); Cleavage: None (fractures conchoidally); Specific gravity: 2.65
- Hardness
- 7 on Mohs scale
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on Mohs scale; Color: Typically white to gray, can be pink or reddish due to iron oxide; 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 high heat and tectonic pressure, commonly over millions of years in mountain-building regions.
Uses & applications
Used in construction, as crushed stone for roadbeds, railway ballast, manufacturing of silica brick, and sometimes as a decorative countertop or ornamental stone.
Geological facts
Unlike sandstone, which crumbles easily, quartzite is exceptionally durable and weathers into resistant ridges. Famous for forming prominent mountain ridges worldwide.
Field identification & locations
Can be identified in the field by its sugary texture, vitreous sparkle from interlocking quartz crystals, and inability to be scratched by a steel knife.
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