metamorphic
Quartzite
Quartzite (Metamorphic Quartz Arenite)
Hardness of 7 on the Mohs scale, color typically white to gray (sometimes tinted pink or red by iron oxide), vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture, specific gravity around 2.65.
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Physical properties
Hardness of 7 on the Mohs scale, color typically white to gray (sometimes tinted pink or red by iron oxide), vitreous to greasy luster, non-foliated massive crystal structure, conchoidal fracture, specific gravity around 2.65.
Formation & geological history
Formed from quartz-rich sandstone or chert through the process of regional or contact metamorphism, where intense heat and pressure cause quartz grains to recrystallize and interlock.
Uses & applications
Used in construction, as crushed stone for road bases, in railway ballast, for decorative landscaping, and occasionally as a dimension stone or in the manufacture of silica brick.
Geological facts
Because quartz is extremely resistant to weathering, quartzite ridges often form prominent, durable mountain crests and hills resistant to erosion.
Field identification & locations
Can be identified in the field by its hard, sugary texture where breaking through the rock occurs across the quartz grains rather than around them, distinguishing it from sandstone. Found worldwide.
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