igneous
Rounded granitic pebble
Granite, a quartz–feldspar-rich plutonic rock
AI-generated identification · may be incorrectFine- to medium-grained, speckled gray-beige with dark mineral flecks and a dull, granular surface; typically composed of quartz, feldspars, and biotite or hornblende. Individual minerals have Mohs hardness around 6–7 (feldspar ~6); granite has no consistent cleavage as a whole.
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Physical properties
Fine- to medium-grained, speckled gray-beige with dark mineral flecks and a dull, granular surface; typically composed of quartz, feldspars, and biotite or hornblende. Individual minerals have Mohs hardness around 6–7 (feldspar ~6); granite has no consistent cleavage as a whole.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in the crust, commonly during continental mountain-building; granite occurs in rocks spanning billions of years. Its rounded shape likely developed through weathering and abrasion during transport.
Uses & applications
Granite is widely used for building stone, paving, countertops, and aggregate; this small pebble is mainly suitable for collecting or decoration.
Geological facts
The visible black-and-light speckling is characteristic of interlocking mineral grains rather than a single mineral crystal.
Field identification & locations
Look for a hard, crystalline, speckled texture with no layering; quartz grains resist scratching by a steel knife. Granite pebbles are common in streams, beaches, and glacial deposits near or downstream from granitic bedrock.
