metamorphic
Red Quartzite River Stone
Quartzite (SiO2)
Hardness: 7 Mohs; Color: Reddish-pink to terracotta; Luster: Vitreous to dull; Crystal Structure: Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7
- Hardness
- 7 Mohs
- Color
- Reddish-pink to terracotta
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 Mohs; Color: Reddish-pink to terracotta; Luster: Vitreous to dull; Crystal Structure: Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone. High heat and pressure cause the sand grains to recrystallize into an interlocking mosaic of quartz crystals. Its rounded shape indicates extensive erosion in a river or coastal environment.
Uses & applications
Used in landscaping, construction aggregate, railway ballast, and occasionally polished for use in artisanal jewelry or as pocket stones.
Geological facts
Quartzite is so tough that it often breaks through the internal sand grains rather than around them. The red coloration is typically caused by trace amounts of hematite or other iron oxides present during formation.
Field identification & locations
Identify in the field by its superior hardness (it will scratch glass) and its sugary, crystalline texture upon fracture. Commonly found in glaciated regions or riverbeds proximal to metamorphic mountain belts like the Appalachians or Alps.
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