metamorphic
Quartzite
Quartz-rich metamorphic rock; chiefly SiO₂
AI-generated identification · may be incorrectTypically white, cream, or gray with a sugary, granular texture and glassy-to-dull luster; Mohs hardness about 7, no cleavage, and high specific gravity around 2.6. The specimen appears to be a weathered, pale quartz-rich rock, though photograph-only identification is not definitive.
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Physical properties
Typically white, cream, or gray with a sugary, granular texture and glassy-to-dull luster; Mohs hardness about 7, no cleavage, and high specific gravity around 2.6. The specimen appears to be a weathered, pale quartz-rich rock, though photograph-only identification is not definitive.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during regional or contact metamorphism, commonly during mountain building. Its age depends on the source formation and may range from Precambrian to recent metamorphic belts.
Uses & applications
Used as crushed stone, aggregate, road material, dimension stone, countertops, flooring, and decorative material; attractive varieties are collected or used ornamentally.
Geological facts
Quartzite resists weathering and often forms ridges and durable landscapes. Unlike sandstone, it usually breaks across quartz grains rather than around them.
Field identification & locations
Common in metamorphic mountain belts worldwide, including Brazil, India, the Alps, and the Appalachian Mountains. A glassy appearance, very hard surface, and inability to scratch it with a steel knife support identification; acid typically produces no reaction.
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