metamorphic
Quartzite
Metamorphic Quartz Sandstone
Hardness of 7 on the Mohs scale, colors range from white and grey to pink, red, and purple due to iron oxides, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, conchoidal fracture, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from white and grey to pink, red, and purple due to iron oxides, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, conchoidal fracture, specific gravity around 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone under intense heat and pressure, typically during tectonic mountain-building events. Geological age varies widely from Precambrian to Cenozoic.
Uses & applications
Used in construction, as crushed stone for road bases, railway ballast, building facades, and manufacturing refractory bricks and silica.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why ridges formed of quartzite often persist as high mountain ranges or resistant hills.
Field identification & locations
Can be identified in the field by its sugary texture on broken surfaces, extreme hardness (scratches glass easily), and the fact that it breaks across quartz grains rather than around them, unlike sandstone.
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