igneous
Tumbled granite pebble
Granite, a coarse-grained felsic intrusive igneous rock
AI-generated identification · may be incorrectMottled tan, gray, and black with a polished, nonmetallic luster; typically composed of quartz, feldspar, and mica or other dark minerals. Hardness is about 6–7 Mohs; crystals are interlocking, with no consistent cleavage in the whole rock.
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Physical properties
Mottled tan, gray, and black with a polished, nonmetallic luster; typically composed of quartz, feldspar, and mica or other dark minerals. Hardness is about 6–7 Mohs; crystals are interlocking, with no consistent cleavage in the whole rock.
Formation & geological history
Formed when silica-rich magma cooled slowly beneath Earth’s surface, allowing visible crystals to grow; granites occur from ancient Precambrian rocks to much younger bodies. The rounded shape and shine indicate tumbling or natural abrasion.
Uses & applications
Used as dimension stone, countertops, paving, and aggregate; small polished pebbles are popular for crafts and collecting.
Geological facts
Granite is a rock rather than a single mineral, and its exact appearance varies with the proportions of feldspar, quartz, and dark minerals.
Field identification & locations
Identify it by its speckled, interlocking grains and lack of layering; granite is widespread in continental crust worldwide. The image shows a small polished pebble, so mineral proportions and locality cannot be determined reliably.
