metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale; colors range from white and gray to pink, purple, or yellowish-brown due to iron oxide impurities; vitreous to greasy luster; non-foliated, granular crystal structure with interlocking quartz grains.
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 of 7 on the Mohs scale; colors range from white and gray to pink, purple, or yellowish-brown due to iron oxide impurities; vitreous to greasy luster; non-foliated, granular crystal structure with interlocking quartz grains.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or chert under intense heat and tectonic pressure, typically during mountain-building events (orogenies) over millions of years.
Uses & applications
Used widely in construction as crushed stone for roadbeds, railway ballast, building facades, decorative landscaping, and occasionally for high-grade silica in manufacturing.
Geological facts
Unlike sandstone, which breaks around the sand grains, quartzite breaks straight through the quartz grains due to the extreme recrystallization welding them together.
Field identification & locations
Can be identified in the field by its extreme hardness (scratches glass easily), inability to effervesce with acid, and the sugary, sparkling appearance of fractured surfaces. Common worldwide in ancient fold belts.
More like this
