metamorphic
Quartzite
Metamorphic Rock (Quartzite), primarily SiO2
Hardness (7 on Mohs scale), color typically ranges from white to gray or reddish-brown (due to iron oxides), sugary/granular texture, vitreous luster on fresh surfaces, non-foliated.
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Physical properties
Hardness (7 on Mohs scale), color typically ranges from white to gray or reddish-brown (due to iron oxides), sugary/granular texture, vitreous luster on fresh surfaces, non-foliated.
Formation & geological history
Formed through the regional or contact metamorphism of quartz-rich sandstone. Under high pressure and temperature, the individual quartz grains recrystallize and fuse together.
Uses & applications
Used in construction as road ballast, roofing granules, and as a decorative stone. High-purity quartzite is used to produce ferrosilicon and industrial silica sand.
Geological facts
Quartzite is so tough that it often survives intense weathering better than most other rocks, frequently forming the caps of ridges and mountains.
Field identification & locations
Can be identified by its inability to be scratched by a steel blade and its tendency to break across quartz grains rather than around them. Found globally in ancient mountain belts.
