metamorphic
Quartzite
Metamorphic Quartz Rock (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 of 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 of 2.65.
Formation & geological history
Formed when quartz-rich sandstone or chert is subjected to high temperatures and pressures usually associated with tectonic compression during mountain building events. Geological age can range from Precambrian to Cenozoic.
Uses & applications
Used in construction as crushed stone for roadbeds, railway ballast, dimension stone, manufacturing refractory bricks, and occasionally as decorative stone or countertops.
Geological facts
Quartzite is extremely durable and resistant to weathering, which is why ridges formed of quartzite often persist as prominent mountain crests. Unlike sandstone, when fractured, quartzite breaks across the quartz grains rather than around them.
Field identification & locations
Can be identified in the field by its sugary texture on weathered surfaces, inability to be scratched by a steel knife, and its failure to effervesce with dilute hydrochloric acid. It is found worldwide in ancient mountain belts.
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