metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale; colors range from white and gray to pink, red, or yellow due to iron oxides; non-foliated texture; vitreous to greasy luster; conchoidal fracture.
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Physical properties
Hardness of 7 on the Mohs scale; colors range from white and gray to pink, red, or yellow due to iron oxides; non-foliated texture; vitreous to greasy luster; conchoidal fracture.
Formation & geological history
Formed when quartz-rich sandstone or chert is subjected to high heat and pressure, typically through tectonic compression in orogenic belts.
Uses & applications
Used in construction, as crushed stone for roadbeds, in manufacturing railroad ballast, for decorative facing stone, and in making refractory bricks and silica blocks.
Geological facts
Unlike sandstone, which breaks around the individual sand grains, quartzite breaks straight through the grains because the quartz cement has fused them together so tightly.
Field identification & locations
Extremely resistant to weathering and erosion, often forming prominent ridges and hills. Found worldwide, particularly in mountain ranges and ancient cratons.
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