metamorphic
Red Quartzite
Quartzite (Metamorphosed Quartz Arenite)
Hardness: 7 on the Mohs scale; Color: Red to reddish-brown due to iron oxide impurities; Luster: Vitreous to greasy; Crystal structure: Interlocking mosaic of quartz crystals; Cleavage: None (fractures conchoidally); Specific gravity: 2.65 - 2.70.
- Hardness
- 7 on the Mohs scale
- Color
- Red to reddish-brown due to iron oxide impurities
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale; Color: Red to reddish-brown due to iron oxide impurities; Luster: Vitreous to greasy; Crystal structure: Interlocking mosaic of quartz crystals; Cleavage: None (fractures conchoidally); Specific gravity: 2.65 - 2.70.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone (quartz arenite) under high temperatures and tectonic pressures, typically in mountain-building events (orogens) over hundreds of millions of years.
Uses & applications
Used in construction, as crushed stone for roadbeds, railway ballast, manufacturing silica bricks, and occasionally as an ornamental stone or for landscaping.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why mountains made of quartzite often form prominent ridges and peaks.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), lack of visible fossils, granular sugary texture on broken surfaces, and the inability of quartz grains to be rubbed off easily (unlike softer sandstones).
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