metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 on Mohs scale (scratches glass). Color: Usually white, gray, or pink/reddish due to iron oxides. Luster: Vitreous to dull. Structure: Granoblastic texture, non-foliated. Cleavage: Indistinct; exhibits conchoidal fracture through grains.
- Hardness
- 7 on Mohs scale (scratches glass)
- Color
- Usually white, gray, or pink/reddish due to iron oxides
- Luster
- Vitreous to dull
Identified More metamorphic →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 7 on Mohs scale (scratches glass). Color: Usually white, gray, or pink/reddish due to iron oxides. Luster: Vitreous to dull. Structure: Granoblastic texture, non-foliated. Cleavage: Indistinct; exhibits conchoidal fracture through grains.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone. High heat and pressure cause the original quartz grains to recrystallize and fuse together. It can range in age from Precambrian to Cenozoic depending on the mountain-building event.
Uses & applications
Used extensively in construction as crushed stone for road bases and railroad ballast. In high-purity forms, it is used to produce glass and silica brick. Polished slabs are used for countertops and floor tiles.
Geological facts
Quartzite is so durable that it often forms the crests of mountain ridges because it resists weathering better than surrounding rocks. It is frequently mistaken for marble, but can be distinguished by its superior hardness (marble is easily scratched by steel, quartzite is not).
Field identification & locations
Identify in the field by its sugary texture and extreme hardness. Unlike sandstone, which breaks around grains, quartzite breaks across the grains. Common in folded mountain belts like the Appalachians or the Alps.
More like this
