metamorphic
Quartzite
Quartzite (SiO2)
AI-generated identification · may be incorrectHardness: 7 (Mohs scale), Color: White to light gray, Luster: Vitreous to dull, Crystal structure: Trigonal/Hexagonal (granular texture), Specific gravity: 2.6-2.7
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Physical properties
Hardness: 7 (Mohs scale), Color: White to light gray, Luster: Vitreous to dull, Crystal structure: Trigonal/Hexagonal (granular texture), Specific gravity: 2.6-2.7
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during mountain-building events. Geological age varies widely from Precambrian to Cenozoic.
Uses & applications
Used in construction as crushed stone or road ballast, as a refractory material in glass making, and for decorative stone in architecture and landscaping.
Geological facts
Quartzite is so tough that it often outlasts surrounding rocks; when broken, it breaks through the quartz grains rather than around them, which distinguishes it from sandstone.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Commonly found in ancient mountain belts like the Appalachians or the Alps.
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