metamorphic
Quartzite
Quartzite (primarily SiO2)
Hardness: 7 on Mohs scale; Color: typically white to gray, often pink or reddish due to iron oxides; Luster: glassy to dull; Structure: non-foliated, interlocking quartz crystals; Cleavage: none (fractures conchoidally)
- Hardness
- 7 on Mohs scale
- Luster
- glassy to dull
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 Mohs scale; Color: typically white to gray, often pink or reddish due to iron oxides; Luster: glassy to dull; Structure: non-foliated, interlocking quartz crystals; Cleavage: none (fractures conchoidally)
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, usually at convergent plate boundaries. This causes the original sand grains to recrystallize into a dense, interlocking mosaic.
Uses & applications
Used in construction as crushed stone for road grit and railroad ballast, in architecture as decorative stone or countertops, and as a source of silica in glass manufacturing.
Geological facts
Quartzite is so durable that it often forms the resistant caps of ridges and mountain ranges. It is harder than the steel of a pocketknife, which is a key way to distinguish it from similar-looking marble.
Field identification & locations
Identify in the field by its extreme hardness (it will scratch glass) and its sugary, crystalline texture that breaks through the grains rather than around them. Found globally in ancient mountain belts.
More like this
