metamorphic
Red Quartzite
Quartzite (primarily SiO2 with hematite inclusions)
Hardness: 7 (Mohs); Color: Red, reddish-brown, or pink; Luster: Vitreous to dull; Structure: Granular, crystalline; Cleavage: None; SG: 2.6-2.7
- Hardness
- 7 (Mohs)
- Color
- Red, reddish-brown, or pink
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 (Mohs); Color: Red, reddish-brown, or pink; Luster: Vitreous to dull; Structure: Granular, crystalline; Cleavage: None; SG: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause quartz grains to recrystallize and fuse together. The red color is typically due to iron oxide (hematite) staining.
Uses & applications
Used as decorative stone, construction aggregate, railway ballast, and occasionally for lapidary work or aquarium decor.
Geological facts
Quartzite is so hard that it can scratch glass and steel. In the field, it can be distinguished from sandstone because it breaks through the quartz grains rather than around them.
Field identification & locations
Identify by its extreme hardness and grainy but fused appearance. Commonly found in mountain ranges or glacial till across North America and Europe.
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