metamorphic
Quartzite
Metamorphic Quartz Sandstone
Hardness of 7 on the Mohs scale, colors ranging from white and gray to pink, yellow, or brown due to iron oxide impurities, vitreous to greasy luster, massive to granular crystal structure, no good cleavage, specific gravity of 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors ranging from white and gray to pink, yellow, or brown due to iron oxide impurities, vitreous to greasy luster, massive to granular crystal structure, no good cleavage, specific gravity of 2.65.
Formation & geological history
Formed when quartz-rich sandstone is subjected to high heat and pressure, typically during tectonic compression in orogenic belts. Geological age can range from Precambrian to Cenozoic.
Uses & applications
Used in construction, as crushed stone for road bases, in railroad ballast, for decorative landscaping, and occasionally for specialty glass and refractory brick manufacturing.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why ridges formed of quartzite often persist as prominent hills or mountains in eroded landscapes.
Field identification & locations
Can be identified in the field by its extreme hardness (scratches glass easily), sugary texture on fractured surfaces, and the fact that it breaks across quartz grains rather than around them like sandstone. Found worldwide.
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