metamorphic
Red Quartzite (likely Purple/Red variety)
Quartzite (SiO2)
Hardness: 7 (Mohs scale); Color: Pinkish-red to purple; Luster: Vitreous to dull/sandy; Crystal structure: Trigonal/Hexagonal system (microcrystalline); Specific gravity: 2.6–2.7; Cleavage: None (conchoidal fracture).
- Hardness
- 7 (Mohs scale)
- Color
- Pinkish-red to purple
- Luster
- Vitreous to dull/sandy
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Physical properties
Hardness: 7 (Mohs scale); Color: Pinkish-red to purple; Luster: Vitreous to dull/sandy; Crystal structure: Trigonal/Hexagonal system (microcrystalline); Specific gravity: 2.6–2.7; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure Recrystallize the quartz grains, interlocking them into a dense, hard mass. Often found in Proterozoic rock formations.
Uses & applications
Used primarily in construction as crushed stone for road beds or railway ballast. Also used as decorative landscaping stone, architectural cladding, and occasionally for lapidary work (polishing/tumbling).
Geological facts
Quartzite is so hard that it will scratch glass and even steel. The reddish-purple hue is usually caused by small amounts of hematite (iron oxide) trapped between the quartz grains during formation.
Field identification & locations
Identify in the field by its sugary texture on broken surfaces and extreme hardness (will not react with acid, unlike limestone). Commonly found in glaciated regions (drifts), mountain ranges, and as smoothed pebbles on beaches.
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