metamorphic
Weathered quartz-rich metamorphic rock (probable quartzite)
Quartzite, primarily microcrystalline quartz (SiO₂), with possible iron-oxide staining and minor mica/feldspar
AI-generated identification · may be incorrectHardness about 7 Mohs; brown, gray, cream, and rusty-orange coloration; vitreous to dull luster; granular interlocking quartz texture, with no obvious cleavage. The rusty tones likely reflect limonite/goethite coatings or alteration.
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Physical properties
Hardness about 7 Mohs; brown, gray, cream, and rusty-orange coloration; vitreous to dull luster; granular interlocking quartz texture, with no obvious cleavage. The rusty tones likely reflect limonite/goethite coatings or alteration.
Formation & geological history
Quartzite forms when quartz-rich sandstone is recrystallized under heat and pressure during metamorphism, commonly in Precambrian or younger mountain belts. This hand specimen appears strongly weathered and iron-stained.
Uses & applications
Used as crushed aggregate, road stone, building stone, and decorative material; attractive pieces may be collected or polished, though this specimen appears modest in quality.
Geological facts
Quartzite commonly resists weathering more strongly than surrounding rocks and forms ridges or resistant outcrops. Its grains tend to fracture through the rock rather than around individual grains.
Field identification & locations
Likely identification can be tested by scratching glass with a fresh edge and checking for a sugary, fused quartz texture; a steel knife should not scratch it. Common occurrences include metamorphic belts worldwide, including India, Brazil, the United States, and Africa.
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