metamorphic
Quartzite
Metamorphic Quartz Rock (SiO2)
Hardness of 7 on the Mohs scale, typically white to gray or yellowish-brown due to iron oxide staining, vitreous to greasy luster, non-foliated crystal structure, conchoidal fracture with no true cleavage, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically white to gray or yellowish-brown due to iron oxide staining, vitreous to greasy luster, non-foliated crystal structure, conchoidal fracture with no true cleavage, specific gravity around 2.65.
Formation & geological history
Formed under high heat and pressure from quartz sandstone during regional or contact metamorphism, dating across various geological eras from Precambrian to Cenozoic.
Uses & applications
Used in construction, as crushed stone for roadbeds, railway ballast, manufacturing of silica bricks, and occasionally as a decorative countertop or lapidary material.
Geological facts
Quartzite is extremely resistant to weathering and erosion, which is why ridges formed of quartzite often remain as prominent hills or mountain ranges after softer surrounding rocks have eroded away.
Field identification & locations
Identified by its high hardness (scratches glass easily), inability to be split along bedding planes like sandstone, and sugary texture on fresh breaks. Found worldwide in mountainous and ancient cratonic regions.
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