igneous
Rounded granite or granitic gneiss pebble
Granite; mainly quartz, feldspar, and mica (exact identification is uncertain from the photograph)
AI-generated identification · may be incorrectCoarse granular, gray-brown, and dull to slightly sparkly, with visible dark mica or mafic minerals. Typical granite hardness is about 6–7 Mohs; it has interlocking crystals and no cleavage as a whole.
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Physical properties
Coarse granular, gray-brown, and dull to slightly sparkly, with visible dark mica or mafic minerals. Typical granite hardness is about 6–7 Mohs; it has interlocking crystals and no cleavage as a whole.
Formation & geological history
Likely an eroded and water-rounded fragment of continental crust, formed when silica-rich magma slowly crystallized underground, generally during Precambrian or younger intrusive events.
Uses & applications
Common granite is used as crushed aggregate, building stone, paving, and monuments; attractive pieces may be collected but this specimen has little commercial value.
Geological facts
The rounded shape indicates transport by water, ice, or sediment abrasion. The dark streak may represent biotite-rich material, a mafic inclusion, or weathering.
Field identification & locations
Look for distinct quartz grains, pink/white feldspar, and black mica; a glassy streak or strong reaction to acid would suggest another material. Common worldwide, especially in stream gravels near granitic terrains.
