metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, colors range from white and gray to pink, brown, and red, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, lacks distinct cleavage, specific gravity of approximately 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, colors range from white and gray to pink, brown, and red, vitreous to greasy luster, massive crystal structure with interlocking quartz grains, lacks distinct cleavage, specific gravity of approximately 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert under high temperatures and pressures associated with tectonic compression during regional metamorphism.
Uses & applications
Used in construction as crushed stone for road bases, railway ballast, building stone, manufacturing silica brick, and occasionally for decorative landscaping or countertops.
Geological facts
Because quartz is extremely resistant to weathering, quartzite ridges often form prominent mountain crests and hills resistant to erosion.
Field identification & locations
Can be identified in the field by its hardness (scratches glass easily), lack of reactivity to acid, and sugary textured fractured surfaces where quartz grains break through rather than around the cement.
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