metamorphic
Quartzite
Metamorphic rock (SiO2)
Hardness 7 on Mohs scale; Color: typically white, gray, or tan with some reddish iron staining; Luster: vitreous to dull; Crystal structure: hexagonal microcrystalline structure; Specific Gravity: 2.63-2.65.
- Luster
- vitreous to dull
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Physical properties
Hardness 7 on Mohs scale; Color: typically white, gray, or tan with some reddish iron staining; Luster: vitreous to dull; Crystal structure: hexagonal microcrystalline structure; Specific Gravity: 2.63-2.65.
Formation & geological history
Formed through the regional metamorphism of quartz sandstone. High pressure and temperature cause the quartz grains to recrystallize and fuse together, often during mountain-building events.
Uses & applications
Used in construction as crushed stone for road beds, in manufacturing glass and ceramics, as an abrasive, and occasionally for decorative stone or arrowheads due to its conchoidal fracturing.
Geological facts
Quartzite is so tough that it often outlasts the rocks around it, resulting in resistant ridges and mountain caps. It is one of the most durable and weather-resistant rocks found on Earth.
Field identification & locations
Identify in the field by its hardness (it scratches glass easily) and its sugary, crystalline texture; unlike sandstone, it breaks through the grains rather than around them. Common in folded mountain belts and ancient shield regions.
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