metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, typically white, gray, or pinkish in color, vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture with no true cleavage, and a specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically white, gray, or pinkish in color, vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture with no true cleavage, and a specific gravity around 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through regional or contact metamorphism involving high heat and pressure, which recrystallizes the quartz grains into an interlocking mosaic.
Uses & applications
Used in construction, railroad ballast, manufacturing of silica bricks, decorative aggregates, and occasionally as a dimension stone for countertops and wall tiles.
Geological facts
Pure quartzite is one of the most chemically inert and physically durable rocks on Earth, making it extremely resistant to weathering and erosion.
Field identification & locations
Can be identified in the field by its inability to be scratched by a knife or glass, its granular sugar-like fractured surface, and lack of acid reaction with hydrochloric acid.
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