metamorphic
Weathered quartzite (probable)
Quartzite; predominantly microcrystalline quartz (SiO₂), with possible iron-oxide staining and mica/clay impurities
AI-generated identification · may be incorrectHardness about 7 Mohs; tan-brown, gray, and rusty-gold coloration; dull to sugary/vitreous luster; massive, granular texture with no obvious cleavage and irregular fracture. The rounded shape and surface patina indicate substantial weathering or water transport.
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Physical properties
Hardness about 7 Mohs; tan-brown, gray, and rusty-gold coloration; dull to sugary/vitreous luster; massive, granular texture with no obvious cleavage and irregular fracture. The rounded shape and surface patina indicate substantial weathering or water transport.
Formation & geological history
Formed when quartz-rich sandstone recrystallized under heat and pressure during regional metamorphism, generally in Precambrian to younger mountain belts. Iron-bearing minerals later oxidized, producing the brown and golden staining.
Uses & applications
Used as durable aggregate, paving and building stone, decorative stone, and occasionally as a lapidary or display specimen. This example has modest collector value unless provenance or unusual mineral inclusions are documented.
Geological facts
Quartzite is typically more resistant to weathering than the sandstone from which it formed, so it commonly survives as rounded stream cobbles or resistant ridges.
Field identification & locations
Identify it by scratching glass, showing little or no reaction to dilute hydrochloric acid, and observing fused quartz grains rather than obvious sand grains or bedding. Common worldwide in metamorphic belts and quartz-rich river gravels.
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