metamorphic
Quartzite (with Iron Staining)
Metamorphic Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: Pinkish-brown to grey; Luster: Vitreous to dull; Crystal structure: Hexagonal (as quartz); High specific gravity around 2.65.
- Hardness
- 7 on Mohs scale
- Color
- Pinkish-brown to grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: Pinkish-brown to grey; Luster: Vitreous to dull; Crystal structure: Hexagonal (as quartz); High specific gravity around 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, usually in orogenic belts. This specific specimen shows oxidative iron staining.
Uses & applications
Commonly used as crushed stone for road construction, railway ballast, and sometimes as a decorative stone in landscaping or as a refractory material.
Geological facts
Quartzite is so tough that it often survives erosion better than the surrounding rock, forming resistant ridges and hilltops. It is one of the hardest common rocks found.
Field identification & locations
Identified by its sugary texture and the fact that it will easily scratch glass. Usually found in mountainous regions or as rounded pebbles in glacial drift.
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