metamorphic
Quartzite
Quartzite (predominantly SiO2)
Hardness: 7 on Mohs scale; Color: yellow, orange, or reddish due to iron oxides; Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None
- Hardness
- 7 on Mohs scale
- Color
- yellow, orange, or reddish due to iron oxides
- Luster
- Vitreous to dull
Identified More metamorphic →
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Physical properties
Hardness: 7 on Mohs scale; Color: yellow, orange, or reddish due to iron oxides; Luster: Vitreous to dull; Structure: Granular, non-foliated; Cleavage: None
Formation & geological history
Formed through the metamorphism of quartz sandstone under high heat and pressure, causing the original quartz grains to recrystallize and fuse together into a dense, hard rock.
Uses & applications
Used as a decorative stone in landscaping, as crushed stone for road construction, and historically for making stone tools due to its hardness and conchoidal fracturing.
Geological facts
Quartzite is so hard and chemically resistant that it often forms the caps of hills and ridges because it resists erosion much better than surrounding rocks.
Field identification & locations
Identify in the field by its hardness (it can scratch glass) and its grainy, sugary texture. Unlike sandstone, it will break across the grains rather than around them.
