metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, typically gray, white, or reddish in color with a vitreous to greasy luster, non-foliated massive crystal structure, poor cleavage, and a specific gravity of approximately 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically gray, white, or reddish in color with a vitreous to greasy luster, non-foliated massive crystal structure, poor cleavage, and a specific gravity of approximately 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through regional or contact metamorphism involving high temperatures and pressures, typically originating in mountain-building belts over millions of years.
Uses & applications
Used in construction, as a decorative building stone, in the production of silica brick, and sometimes as a gemstone or in landscaping.
Geological facts
Quartzite is extremely durable and resistant to weathering, which explains why mountains made of quartzite often form the highest ridges and peaks.
Field identification & locations
Can be identified in the field by its sugary texture on broken surfaces, extreme hardness that scratches glass easily, and the lack of fizz when tested with hydrochloric acid. Common worldwide in ancient orogenic belts.
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