metamorphic
Red Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: Reddish-pink to rust; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7.
- Hardness
- 7 on Mohs scale
- Color
- Reddish-pink to rust
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-pink to rust; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone subjected to high heat and pressure, causing the individual quartz grains to recrystallize and fuse together. Red coloration is typically due to hematite or iron oxide impurities.
Uses & applications
Used in construction as crushed stone or road ballast, as decorative garden stone, in glass manufacturing if pure, and sometimes for lapidary work.
Geological facts
Quartzite is so tough that it often breaks through the internal quartz grains rather than around them. It is one of the most durable rocks on the Earth's surface.
Field identification & locations
Identify in the field by its superior hardness (can scratch glass) and its grainy, sandpaper-like texture that cannot be rubbed off. It is commonly found in mountain ranges and ancient metamorphic shields.
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