metamorphic
Quartzite
Quartzite (SiO2)
Hardness: 7 (Mohs scale), Color: White to light gray, Luster: Vitreous to dull, Crystal Structure: Trigonal (granular), Cleavage: None (conchoidal fracture), Specific Gravity: 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: 7 (Mohs scale), Color: White to light gray, Luster: Vitreous to dull, Crystal Structure: Trigonal (granular), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, typically during tectonic plate collisions and mountain building.
Uses & applications
Used in construction as crushed stone for road gravel, as decorative building stone, and historically as a raw material for stone tools (though less commonly than flint or chert).
Geological facts
Quartzite is so hard that it can scratch steel; it is often more durable than the parent sandstone it originated from, causing it to form prominent ridges and peaks in mountain ranges.
Field identification & locations
Identify in the field by its sugary texture and extreme hardness (cannot be scratched by a knife). Commonly found in ancient mountain ranges such as the Appalachians or the Alps.
More like this
