metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on the Mohs scale; Color: Grayish-white to tan; Luster: Vitreous to dull; Crystal structure: Hexagonal (trigonal); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.6 to 2.7.
- Hardness
- 7 on the Mohs scale
- Color
- Grayish-white to tan
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on the Mohs scale; Color: Grayish-white to tan; Luster: Vitreous to dull; Crystal structure: Hexagonal (trigonal); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.6 to 2.7.
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure. This specimen is a rounded river pebble, shaped by water erosion over long periods.
Uses & applications
Used in construction as road ballast, in glassmaking, and as a decorative stone in landscaping or interior design.
Geological facts
Quartzite is so tough that it can often cut through glass and is much harder than common river stones made of limestone or marble. It can remain as a prominent ridge in mountainous areas because it is highly resistant to weather.
Field identification & locations
Identify by its ability to scratch glass and its granular, sugary appearance when broken. Commonly found in riverbeds, glacial deposits, and mountain ranges. Its rounded shape indicates it has traveled far from its source in a high-energy water environment.
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