metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale; Color: typically white, gray, or reddish due to iron oxides; Luster: Vitreous to dull; Crystal structure: Trigonal; Fracture: Conchoidal; Specific gravity: 2.6-2.7
- Hardness
- 7 on Mohs scale
- Color
- typically white, gray, or reddish due to iron oxides
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on Mohs scale; Color: typically white, gray, or reddish due to iron oxides; Luster: Vitreous to dull; Crystal structure: Trigonal; Fracture: Conchoidal; Specific gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of quartz-rich sandstone under intense heat and pressure, where quartz grains recrystallize and fuse together.
Uses & applications
Used in construction as crushed stone for road grit and railroad ballast, in glassmaking due to its high silica content, and as a decorative stone in architecture.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rock in weathering processes, frequently forming the tops of ridges and resistant hills.
Field identification & locations
Identify in the field by its extreme hardness (cannot be scratched by steel) and a texture that breaks through the quartz grains rather than around them, unlike sandstone.
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