metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically pink, red, or white due to iron oxide impurities; Luster: dull to vitreous; Crystal structure: Non-foliated, granular; Cleavage: None (fractures through grains)
- Hardness
- 7 on Mohs scale
- Color
- typically pink, red, or white due to iron oxide impurities
- Luster
- dull to vitreous
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Physical properties
Hardness: 7 on Mohs scale; Color: typically pink, red, or white due to iron oxide impurities; Luster: dull to vitreous; Crystal structure: Non-foliated, granular; Cleavage: None (fractures through grains)
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under high heat and pressure, typically during mountain-building events (orogeny). Common in Precambrian and Paleozoic formations.
Uses & applications
Used in construction as crushed stone or decorative facing, high-grade quartzite is used to produce silica sand for glassmaking and industrial abrasives.
Geological facts
Quartzite is so tough that it often forms the ridges of mountain ranges because it resists erosion much better than surrounding softer rocks.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Often found in glaciated regions as rounded river or beach stones.
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