metamorphic
Red Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Reddish-brown due to iron oxide impurities; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown due to iron oxide impurities
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-brown due to iron oxide impurities; Luster: Vitreous to dull; Crystal structure: Hexagonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone. High heat and pressure causes the individual quartz grains to recrystallize and fuse together. Often associated with Proterozoic or Paleozoic geological formations.
Uses & applications
Used in construction as crushed stone or decorative ballast, as a dimension stone for architecture, and occasionally in the manufacture of glass or ceramics due to high silica content.
Geological facts
Quartzite is so tough that it often breaks through the individual quartz grains rather than around them, which distinguishes it from sandstone. The red color is usually indicative of hematite (iron oxide) staining within the matrix.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by a steel knife) and its grainy but fused texture. Commonly found in mountain ranges or glacial till where ancient sedimentary basins were uplifted.
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