metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: reddish-pink to white (colored by iron oxides); Luster: Vitreous to dull; Crystal structure: Trigonal; Fracture: Conchoidal; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- reddish-pink to white (colored by iron oxides)
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: reddish-pink to white (colored by iron oxides); Luster: Vitreous to dull; Crystal structure: Trigonal; Fracture: Conchoidal; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz sandstone. Subjected to intense heat and pressure, causing quartz grains to recrystallize and fuse together. Often found in Precambrian or Paleozoic metamorphic terrains.
Uses & applications
Used in construction for road ballast and railroad bedding, as dimension stone in architecture, and occasionally as decorative landscaping stone or low-end jewelry/tumbling.
Geological facts
Quartzite is so tough that it usually breaks through the quartz grains rather than along their boundaries, unlike sandstone. It is often harder than steel and can easily scratch glass.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel blade) and its sugary, crystalline texture. Commonly found in mountainous regions or as water-worn pebbles in riverbeds and glacial deposits.
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