metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: White to light gray with beige/tan iron staining; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular microcrystalline texture); Cleavage: None (conchoidal to irregular fracture).
- Hardness
- 7 on Mohs scale
- Color
- White to light gray with beige/tan iron staining
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: White to light gray with beige/tan iron staining; Luster: Vitreous to dull; Crystal structure: Trigonal/Hexagonal (granular microcrystalline texture); Cleavage: None (conchoidal to irregular fracture).
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone subjected to high heat and pressure, causing the original quartz grains to recrystallize and fuse together. Typically found in mountain belts (orogenic zones).
Uses & applications
Used in construction as crushed stone for road ballast, as a decorative stone in landscaping, and sometimes for glassmaking or as a refractory material due to its high silica content.
Geological facts
Quartzite is so tough that it often breaks through the quartz grains rather than along the boundaries between them. It is one of the most durable and weather-resistant rocks on the Earth's surface.
Field identification & locations
Identify in the field by its superior hardness (it will easily scratch glass and steel) and its crystalline, sugary appearance on fresh surfaces. It is found globally in Precambrian and Paleozoic metamorphic terrains.
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