metamorphic
Quartzite
Quartzite, predominantly crystalline SiO₂
AI-generated identification · may be incorrectHardness about 7 Mohs; white to cream with rusty orange-brown iron-oxide staining, vitreous to sugary luster, and interlocking quartz grains. It has no obvious cleavage and commonly breaks irregularly or conchoidally; specific gravity is approximately 2.6–2.7.
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 about 7 Mohs; white to cream with rusty orange-brown iron-oxide staining, vitreous to sugary luster, and interlocking quartz grains. It has no obvious cleavage and commonly breaks irregularly or conchoidally; specific gravity is approximately 2.6–2.7.
Formation & geological history
Forms when quartz-rich sandstone is subjected to heat and pressure, recrystallizing its grains; the original sandstone may be Precambrian to Phanerozoic in age. Iron-bearing fluids commonly create the orange and brown coloration.
Uses & applications
Used as crushed stone, aggregate, road material, building stone, paving, and countertops; attractive pieces are collected or used decoratively, though this specimen appears ordinary rather than gem quality.
Geological facts
Quartzite is generally harder and more resistant to weathering than its sandstone precursor. It can resemble marble, but quartzite does not fizz with dilute hydrochloric acid.
Field identification & locations
Identify it by its granular quartz texture, glassy sparkle, extreme hardness, and inability to scratch with a steel knife; quartz-rich rocks occur worldwide, including Brazil, India, the United States, and Scandinavia.
More like this
