metamorphic
Weathered quartz-rich metamorphic rock, likely quartzite
Quartzite; predominantly quartz (SiO₂), with minor iron-oxide staining and possible mica/clay minerals
AI-generated identification · may be incorrectTypically Mohs hardness 7, gray to brown/rust-colored, with vitreous to dull weathered luster; interlocking granular quartz texture and poor cleavage. The specimen appears strongly weathered and fractured, with rusty limonite/hematite coatings.
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Physical properties
Typically Mohs hardness 7, gray to brown/rust-colored, with vitreous to dull weathered luster; interlocking granular quartz texture and poor cleavage. The specimen appears strongly weathered and fractured, with rusty limonite/hematite coatings.
Formation & geological history
Formed when quartz-rich sandstone was recrystallized under heat and pressure during regional metamorphism; exact age and locality cannot be determined from the photograph. Common in metamorphic mountain belts and ancient shield rocks.
Uses & applications
Used as crushed stone, riprap, road aggregate, wall stone, and architectural facing; attractive varieties are used decoratively but this weathered piece has little jewelry value.
Geological facts
Quartzite is generally harder and more resistant to erosion than its sandstone precursor, often forming ridges and prominent landscape outcrops.
Field identification & locations
Look for grains fused into a hard mass and fractures crossing grains rather than separating them; a steel nail should not scratch fresh quartzite. Common worldwide, including the Appalachians, Rocky Mountains, India, Brazil, and Scandinavia.
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