metamorphic
Quartzite
Metamorphic Quartzite
Hardness of 7 on the Mohs scale, colors ranging from white and gray to pink or brown, vitreous to dull luster, granular crystal structure, conchoidal fracture with no distinct cleavage, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors ranging from white and gray to pink or brown, vitreous to dull luster, granular crystal structure, conchoidal fracture with no distinct cleavage, specific gravity around 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and tectonic pressure, typically during mountain-building events over millions of years.
Uses & applications
Used in construction, as road aggregate, in the manufacturing of railroad ballast, for decorative building stones, and occasionally in countertops.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why quartz sandstone-rich ridges often survive as high mountain ridges while surrounding softer rocks erode.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), sugary texture on fractured surfaces, and lack of reaction to dilute hydrochloric acid. Found worldwide in ancient mountain belts.
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