metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, brown, or yellow due to iron oxide impurities. It has a vitreous to greasy luster on fracture surfaces and a granular crystal structure with interlocking quartz grains.
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Physical properties
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, brown, or yellow due to iron oxide impurities. It has a vitreous to greasy luster on fracture surfaces and a granular crystal structure with interlocking quartz grains.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or chert under high heat and tectonic pressure, typically in mountain-building or orogenic belts over millions of years.
Uses & applications
Used in construction, road aggregates, railway ballast, manufacturing of silica brick, and occasionally as decorative stone or countertops.
Geological facts
Because quartz is extremely resistant to weathering, quartzite mountains often form the highest ridges and most rugged peaks in various mountain ranges, as the original sandstone has been completely recrystallized.
Field identification & locations
Can be identified in the field by its extreme hardness (scratches glass easily) and the characteristic way it breaks across the quartz grains rather than around them, unlike sandstone.
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