metamorphic
Quartzite
Metamorphic Quartzite
Hardness of 7 on the Mohs scale, color typically ranging from white to gray, pink, or reddish due to iron oxides. It has a vitreous to greasy luster, non-foliated massive crystal structure, lack of visible cleavage, and a specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color typically ranging from white to gray, pink, or reddish due to iron oxides. It has a vitreous to greasy luster, non-foliated massive crystal structure, lack of visible cleavage, and a specific gravity around 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or chert under high temperatures and pressures, typically in tectonic orogenic belts. Geologically ancient and widespread globally.
Uses & applications
Used in construction, as road aggregate, railroad ballast, dimension stone, and occasionally in manufacturing refractory bricks and ferrosilicon.
Geological facts
Quartzite is extremely resistant to weathering and chemical action, which is why quartzose sandstone ridges often survive as prominent hills or ridges long after surrounding rocks have eroded away.
Field identification & locations
Can be identified in the field by its hardness (will easily scratch glass and cannot be scratched by a steel knife) and the way it fractures across quartz grains rather than around them, differentiating it from sandstone.
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