metamorphic
Red Quartzite
Metamorphosed Quartz Sandstone (SiO2 with Iron Oxide impurities)
Hardness: 7 on Mohs scale; Color: Reddish-brown to pink due to hematite; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- Reddish-brown to pink due to hematite
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Reddish-brown to pink due to hematite; Luster: Vitreous to dull; Crystal structure: Trigonal (granular); Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events (orogeny). The red color comes from iron oxide staining during or before the metamorphic process.
Uses & applications
Used as decorative stone in landscaping, heavy road construction (crushed stone), railway ballast, and occasionally for high-end countertops or tiles.
Geological facts
Quartzite is so tough that it often breaks through the individual quartz grains rather than around them, unlike sandstone. It is one of the most durable rocks on Earth's surface.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and granular texture that looks like fused sugar. Look for it in glaciated areas or ancient mountain belts.
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