metamorphic
Quartzite
Quartzite (Metamorphosed quartz sandstone)
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, orange, or reddish-brown due to iron oxide impurities, vitreous to greasy luster, non-foliated crystal structure, lacks distinct cleavage, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color ranges from white and gray to pink, orange, or reddish-brown due to iron oxide impurities, vitreous to greasy luster, non-foliated crystal structure, lacks distinct cleavage, 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 orogeny. Geological age varies widely depending on the formation site, ranging from Precambrian to Cenozoic eras.
Uses & applications
Used in construction, as crushed stone for road bases, railway ballast, manufacturing silica bricks, and occasionally as decorative stone or in landscaping.
Geological facts
Quartzite is extremely durable and resistant to chemical weathering, which is why ridges formed of quartzite often persist as prominent mountain crests. The fracture goes through the quartz grains rather than around them, distinguishing it from original sandstone.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), inability to be split along bedding planes easily, and sugary texture on freshly broken surfaces. Common worldwide in mountain belts.
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