igneous
Weathered granite or granitic gneiss pebble
Granite; mainly quartz (SiO₂), feldspar, and mica, with possible gneissic alteration
AI-generated identification · may be incorrectCoarse, mottled white-gray, tan, and brown grains with dull to slightly glassy luster; quartz and feldspar are typically Mohs 6–7, with no obvious cleavage as a whole rock. Rounded edges and brown surface staining indicate weathering and abrasion.
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Physical properties
Coarse, mottled white-gray, tan, and brown grains with dull to slightly glassy luster; quartz and feldspar are typically Mohs 6–7, with no obvious cleavage as a whole rock. Rounded edges and brown surface staining indicate weathering and abrasion.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, likely hundreds of millions to billions of years ago; the rounded shape probably resulted from stream or beach transport and surface weathering.
Uses & applications
Commonly used as crushed stone, aggregate, building stone, and landscaping material; this small weathered piece has little jewelry or industrial value.
Geological facts
The brown coloration is likely iron-oxide staining, while pale patches may be feldspar or weathered quartz. A precise identification would require a fresh broken surface or microscopic examination.
Field identification & locations
Common in continental crust and found widely in streambeds, glacial deposits, and eroded uplands. Look for interlocking light and dark mineral grains; quartz remains glassy and feldspar commonly shows flat cleavage surfaces.
