metamorphic
Quartzite
Metamorphic Quartzite (SiO2)
Hardness of 7 on the Mohs scale, typically yellow, golden, white, or gray in color, vitreous to greasy luster, granular crystal structure with interlocking quartz crystals, conchoidal fracture, specific gravity of 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, typically yellow, golden, white, or gray in color, vitreous to greasy luster, granular crystal structure with interlocking quartz crystals, conchoidal fracture, specific gravity of 2.65.
Formation & geological history
Formed through the metamorphism of quartz-rich sandstone or chert under high temperatures and pressures, typically associated with tectonic mountain-building events over millions of years.
Uses & applications
Used in construction, as crushed stone for roadbeds, in manufacturing railroad ballast, decorative aggregates, countertops, and occasionally as a gemstone or in lapidary work.
Geological facts
Because quartz is extremely durable and resistant to weathering, quartzite ridges often form prominent, resistant hills or mountain crests in the landscape.
Field identification & locations
Identified in the field by its hardness (scratches glass easily), lack of effervescence with acid, and the sugary, granular texture where individual quartz crystals sparkle in the light. Found worldwide.
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