metamorphic
Quartzite
Quartzite (mostly SiO2)
Hardness: 7 (Mohs scale), Color: light gray to tan with translucent areas, Luster: Vitreous to dull, Structure: Granular/crystalline, Cleavage: None (conchoidal fracture)
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: light gray to tan with translucent areas, Luster: Vitreous to dull, Structure: Granular/crystalline, Cleavage: None (conchoidal fracture)
Formation & geological history
Formed from the metamorphism of quartz sandstone under intense heat and pressure, causing quartz grains to recrystallize and fuse together. Often found in ancient mountain belts.
Uses & applications
Used as decorative stone, crushed stone for road construction, railroad ballast, and in the manufacturing of glass and ceramics. Highly valued for durability.
Geological facts
Quartzite is so hard that it will scratch glass and even high-quality steel. It is frequently more resistant to erosion than the rocks that surround it, often forming ridges and hilltops.
Field identification & locations
Identify by its extreme hardness and smooth, water-worn texture if found in riverbeds. It breaks through the quartz grains rather than around them, distinguishing it from sandstone.
More like this
