metamorphic
Red Quartzite
Quartzite (primarily SiO2 with hematite impurities)
Hardness: 7 (Mohs scale); Color: Reddish-pink to brownish-red; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Fracture: Conchoidal to irregular.
- Hardness
- 7 (Mohs scale)
- Color
- Reddish-pink to brownish-red
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs scale); Color: Reddish-pink to brownish-red; Luster: Vitreous to dull; Crystal structure: Trigonal (microcrystalline); Cleavage: None; Fracture: Conchoidal to irregular.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure cause the quartz grains to recrystallize and fuse together. The red color is typically due to the inclusion of iron oxides like hematite during or after formation.
Uses & applications
Used as decorative stone, construction aggregate, railway ballast, and in the production of glass or silica-based products.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, frequently forming ridges or 'peaks' in mountain ranges. It is harder than steel and will easily scratch glass.
Field identification & locations
Identify by its extreme hardness and grainy texture that looks like sandpaper but is smooth to the touch. Unlike sandstone, quartzite breaks through the grains rather than around them. Common in Precambrian shield areas and folded mountain belts.
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