igneous
Rounded granitic cobble
Granite, chiefly quartz, feldspar, and mica; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectCoarse-speckled gray-brown stone with a dull to weakly granular luster, rounded by abrasion, and no obvious cleavage. Typical granite hardness is about 6–7 Mohs and specific gravity 2.63–2.75.
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Physical properties
Coarse-speckled gray-brown stone with a dull to weakly granular luster, rounded by abrasion, and no obvious cleavage. Typical granite hardness is about 6–7 Mohs and specific gravity 2.63–2.75.
Formation & geological history
Likely an erosion-rounded glacial, river, or beach cobble derived from an intrusive granite body that crystallized slowly underground, commonly hundreds of millions to billions of years ago.
Uses & applications
Useful mainly as a landscaping, decorative, or teaching specimen; granite is widely used for aggregate, dimension stone, countertops, monuments, and paving.
Geological facts
The rounded shape indicates prolonged transport or weathering rather than its original intrusive form. Dark flecks may be biotite or hornblende, while lighter grains are feldspar and quartz.
Field identification & locations
Identify it by visible interlocking gray, white, and dark mineral grains and a hard, massive texture; a streak test is white and dilute acid should not fizz. Common around granitic terrains, glacial deposits, and stream gravels.
