metamorphic
Quartzite
Metamorphic Quartz (SiO2)
Hardness: 7 on the Mohs scale; Color: Light gray, buff, creamy yellowish to white; Luster: Vitreous to dull; Structure: Granoblastic, non-foliated metamorphic fabric with fused quartz grains; Cleavage: None (conchoidal fracture).
- Hardness
- 7 on the Mohs scale
- Color
- Light gray, buff, creamy yellowish to white
- Luster
- Vitreous to dull
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Physical properties
Hardness: 7 on the Mohs scale; Color: Light gray, buff, creamy yellowish to white; Luster: Vitreous to dull; Structure: Granoblastic, non-foliated metamorphic fabric with fused quartz grains; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone under intense heat and pressure, recrystallizing the original quartz grains into an interlocking mosaic.
Uses & applications
Used in construction as crushed stone, road ballast, decorative building stone, and occasionally as raw material for silica manufacturing.
Geological facts
Quartzite is so tough and resistant to chemical weathering that it often forms prominent ridges and hilltops. Unlike sandstone, quartzite fractures right through the quartz grains rather than along grain boundaries.
Field identification & locations
Identified in the field by its high hardness (scratches glass easily), sugary texture, and tendency to break across quartz grains. Found in mountain ranges, metamorphic terranes, and glaciated regions globally.
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