metamorphic
Weathered feldspathic quartzite or granitic rock fragment
Quartz-rich silicate rock; exact identification requires thin-section or chemical testing
AI-generated identification · may be incorrectHardness approximately 6–7 Mohs; tan to gray-brown, granular, and dull to slightly vitreous. Visible quartz/feldspar-like grains and dark mineral streaks; no obvious cleavage, with irregular fracture and strong weathering.
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Physical properties
Hardness approximately 6–7 Mohs; tan to gray-brown, granular, and dull to slightly vitreous. Visible quartz/feldspar-like grains and dark mineral streaks; no obvious cleavage, with irregular fracture and strong weathering.
Formation & geological history
Likely derived from metamorphosed sandstone (quartzite) or a weathered granitoid, formed deep in the crust millions to billions of years ago and later exposed. The dark lines may be fractures or iron/manganese staining rather than fossils.
Uses & applications
Primarily a geological or lapidary specimen; quartzite can be used as aggregate, building stone, and paving material, while attractive pieces may be polished.
Geological facts
Its rounded shape and iron-brown surface indicate prolonged weathering or transport. A hardness test, streak test, acid test, and close examination of grain boundaries would distinguish quartzite from granite or gneiss.
Field identification & locations
Common in stream gravels, glacial deposits, and weathered bedrock. Quartzite scratches glass and typically shows interlocking quartz grains; granite usually has distinct visible feldspar, quartz, and mica crystals.
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