metamorphic
Quartzite
Quartzite (Metamorphosed Quartz Sandstone)
Hardness of 7 on the Mohs scale, typically white, gray, or pinkish in color, vitreous to greasy luster, non-foliated crystal structure with interlocking quartz grains, conchoidal fracture, and 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 crystal structure with interlocking quartz grains, conchoidal fracture, and specific gravity around 2.65.
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure, typically through tectonic compression during mountain building events over millions of years.
Uses & applications
Used widely in construction, as crushed stone for roadbeds, railway ballast, dimension stone, building facades, and increasingly as a durable countertop material in interior design.
Geological facts
Because quartzite is composed almost entirely of quartz, it is extremely resistant to chemical weathering and erosion, which is why ancient mountain chains often leave behind ridges capped with quartzite.
Field identification & locations
Can be identified in the field by its very hard nature (it will easily scratch glass and cannot be scratched by a knife blade) and the way it breaks across the quartz grains rather than around them like sandstone. Found worldwide.
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