metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, color ranges from white and grey to pink, red, and purple due to iron oxides, luster is vitreous to greasy on fractured surfaces, crystal structure is a dense interlocking network of quartz grains, cleavage is absent, specific gravity is approximately 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color ranges from white and grey to pink, red, and purple due to iron oxides, luster is vitreous to greasy on fractured surfaces, crystal structure is a dense interlocking network of quartz grains, cleavage is absent, specific gravity is approximately 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert that has been subjected to high heat and pressure, typically through tectonic compression in mountain-building processes (regional metamorphism). Geological age varies widely from Precambrian to Cenozoic.
Uses & applications
Used in construction, as crushed stone for road bases, railway ballast, building facades, decorative landscaping, manufacturing of silica bricks, and occasionally as a gemstone or decorative carving stone.
Geological facts
Quartzite is extremely durable and weather-resistant, which is why ridges formed of quartzite often persist as prominent hills or mountain crests while surrounding rocks erode away.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), the lack of visible separate sand grains breaking apart (unlike sandstone, which fractures around grains, quartzite fractures through the quartz grains), and vitreous luster on broken faces. Found worldwide.
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