metamorphic
Quartz-rich rock, likely quartzite
Quartzite; predominantly crystalline SiO₂
AI-generated identification · may be incorrectHardness about 7 Mohs; pale gray-beige, granular texture, vitreous to dull luster, and no obvious cleavage. The small specimen appears massive and weathered, though the photograph does not permit certain identification.
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Physical properties
Hardness about 7 Mohs; pale gray-beige, granular texture, vitreous to dull luster, and no obvious cleavage. The small specimen appears massive and weathered, though the photograph does not permit certain identification.
Formation & geological history
Forms when quartz-rich sandstone is recrystallized under heat and pressure during regional metamorphism, commonly over millions to billions of years. It occurs in metamorphic mountain belts and ancient exposed terrains.
Uses & applications
Used as crushed stone, aggregate, paving, wall stone, and sometimes decorative material; attractive pieces may be collected but are rarely valuable.
Geological facts
Quartzite commonly breaks across quartz grains rather than around them, making fractured surfaces sparkly or sugary. It can resemble massive quartz, sandstone, or chert.
Field identification & locations
Likely quartzite if it scratches glass and shows fused quartz grains; sandstone usually feels more porous and grains may separate. Common worldwide, including the Appalachians, Rocky Mountains, India, Brazil, and Scandinavia.
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