metamorphic
Quartzite
Metamorphic Quartz Sandstone
Hardness: 7 on the Mohs scale. Color: Generally white to gray, but often stained in various shades of pink, red, or brown by iron oxides. Luster: Vitreous to greasy on fractured surfaces. Crystal structure: Interlocking quartz grains. Cleavage: None, breaks across the grains rather than around them.
- Hardness
- 7 on the Mohs scale
- Luster
- Vitreous to greasy on fractured surfaces
Identified More metamorphic →
Explore Quartzite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on the Mohs scale. Color: Generally white to gray, but often stained in various shades of pink, red, or brown by iron oxides. Luster: Vitreous to greasy on fractured surfaces. Crystal structure: Interlocking quartz grains. Cleavage: None, breaks across the grains rather than around them.
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure, typically through tectonic compression during mountain building events. This metamorphic process causes the original quartz sand grains to recrystallize, fusing them into a dense, extremely hard rock.
Uses & applications
Used in construction as crushed stone for roadbeds, railway ballast, and aggregate in concrete. Also used for decorative building stone, counter tops, and in industrial applications such as the production of ferrosilicon and silicon metal.
Geological facts
Quartzite is extremely resistant to weathering and chemical erosion, which is why ridges formed of quartzite often persist as prominent mountain crests or hills while surrounding softer rocks erode away.
Field identification & locations
Can be identified in the field by its sugary or crystalline texture on broken surfaces and its inability to be scratched by a steel knife, easily scratching glass instead. Common globally wherever ancient mountain building occurred.
More like this
