metamorphic
Quartzite
Quartzite (composed primarily of Quartz, SiO2)
Hardness: 7 (Mohs scale), Color: White to grey/silvery, Luster: Vitreous to pearly, Crystal structure: Hexagonal (microcrystalline), Fracture: Conchoidal to irregular, 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 grey/silvery, Luster: Vitreous to pearly, Crystal structure: Hexagonal (microcrystalline), Fracture: Conchoidal to irregular, Specific gravity: 2.6-2.7
Formation & geological history
Formed from the metamorphism of quartz sandstone under high heat and pressure, where individual quartz grains recrystallize into a locked mosaic of crystals. Typically found in mountain belts (orogenic belts).
Uses & applications
Used in construction as crushed stone or decorative facing, in the manufacturing of glass and ceramics, and as a durable material for kitchen countertops and floor tiles.
Geological facts
Quartzite is so tough that it often outlasts the surrounding rocks; when broken with a hammer, the break will pass through the quartz grains rather than around them, which distinguishes it from sandstone.
Field identification & locations
Identify by its extreme hardness (cannot be scratched by steel) and lack of reaction to acid. Look for a sugary texture that glitters in the light. Found globally in ancient shield regions and folded mountain ranges.
