metamorphic
Weathered quartz-rich rock, possibly chert or quartzite
Likely microcrystalline quartz (SiO₂), but exact identification is uncertain from the photograph
AI-generated identification · may be incorrectTan to brown, irregular and opaque, with a dull to slightly waxy luster and possible iron-oxide staining. Quartz hardness is about Mohs 7; cleavage is absent, fracture is typically conchoidal to irregular, and specific gravity is approximately 2.6.
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Physical properties
Tan to brown, irregular and opaque, with a dull to slightly waxy luster and possible iron-oxide staining. Quartz hardness is about Mohs 7; cleavage is absent, fracture is typically conchoidal to irregular, and specific gravity is approximately 2.6.
Formation & geological history
If quartzite, it formed when quartz-rich sandstone was metamorphosed under heat and pressure; if chert, it formed by silica precipitation or replacement in sedimentary environments. A precise geological age and classification require testing and context.
Uses & applications
Common quartzite is used as aggregate, building stone, and occasionally decorative stone; chert has been used historically for tools. This small weathered fragment has little commercial value.
Geological facts
The brown coloration likely reflects limonite or other iron oxides coating or filling fractures. A steel file should not easily scratch quartz-rich material, while glass may be scratched by a fresh edge.
Field identification & locations
Common in metamorphic terrains, sandstone-derived landscapes, and gravel deposits worldwide; look for granular quartz texture in quartzite or smooth waxy/conchoidal fracture in chert. Estimated value: $1–$10 as an ordinary specimen; higher only with distinctive texture, locality, or provenance.
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