metamorphic
Quartzite
Meta-quartzite (SiO2)
Hardness: 7 on Mohs scale. Color: light grey to bluish-grey. Luster: vitreous to sugary. Grain size: medium, highly interlocking crystalline texture. Specific gravity: 2.65.
- Hardness
- 7 on Mohs scale
- Color
- light grey to bluish-grey
- Luster
- vitreous to sugary
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Physical properties
Hardness: 7 on Mohs scale. Color: light grey to bluish-grey. Luster: vitreous to sugary. Grain size: medium, highly interlocking crystalline texture. Specific gravity: 2.65.
Formation & geological history
Formed when quartz-rich sandstone undergoes intense heat and pressure during regional metamorphism, recrystallizing individual quartz grains into a dense, interlocking matrix.
Uses & applications
Used in construction as crushed stone, dimension stone for flooring and cladding, railway ballast, and occasionally for decorative stone carvings.
Geological facts
Unlike sandstone, which breaks around quartz grains, quartzite breaks directly through the mineral grains due to its tight interlocking crystalline structure.
Field identification & locations
Identified in the field by its extreme hardness (scratches glass easily) and sugary, sparkling fracture surface that cuts across grains rather than around them. Found globally in mountainous metamorphic terrains.
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