metamorphic
Red Quartzite
Quartzite (SiO2)
Hardness: 7 on the Mohs scale. Color: Pink to deep reddish-brown due to iron oxide impurities. Luster: Vitreous to greasy. Crystal structure: Trigonal (microcrystalline quartz grains fused together). Cleavage: None (fractures conchoidally). Specific gravity: 2.65.
- Hardness
- 7 on the Mohs scale
- Color
- Pink to deep reddish-brown due to iron oxide impurities
- Luster
- Vitreous to greasy
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Physical properties
Hardness: 7 on the Mohs scale. Color: Pink to deep reddish-brown due to iron oxide impurities. Luster: Vitreous to greasy. Crystal structure: Trigonal (microcrystalline quartz grains fused together). Cleavage: None (fractures conchoidally). Specific gravity: 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert that has been subjected to heat and pressure through regional or contact metamorphism, causing the original quartz grains to recrystallize and interlock.
Uses & applications
Used in construction as crushed stone for road building, railway ballast, building facades, decorative landscaping, and occasionally as dimension stone or for refractory bricks.
Geological facts
Quartzite is extremely durable and resistant to weathering and chemical erosion, 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 (will easily scratch glass and cannot be scratched by a steel knife), sugary or interlocking granular texture on broken surfaces, and conchoidal fracture. Found worldwide in ancient mountain belts.
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