igneous
Quartz-rich granitic pebble
Weathered granite, chiefly quartz (SiO₂), feldspar, and minor mica
AI-generated identification · may be incorrectLight gray, coarse crystalline, with a dull-to-glassy luster; likely Mohs hardness 6–7, poor cleavage overall, and granular texture. Rounded edges indicate stream or beach transport and weathering.
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Physical properties
Light gray, coarse crystalline, with a dull-to-glassy luster; likely Mohs hardness 6–7, poor cleavage overall, and granular texture. Rounded edges indicate stream or beach transport and weathering.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic mountain-building events; this pebble was later eroded and transported.
Uses & applications
Common granite is used as crushed aggregate, paving stone, monuments, and building stone; this small specimen has mainly educational or decorative value.
Geological facts
The white grains are probably feldspar and quartz, while darker flecks may be biotite or hornblende. Its rounded form reflects abrasion rather than a naturally rounded crystal shape.
Field identification & locations
Identify it by visible interlocking grains, abundant pale quartz/feldspar, and lack of layering or foliation; a steel file should not easily scratch quartz grains. Granitic pebbles occur in many riverbeds, glacial deposits, and coastal gravels.
