igneous
Tumbled granite pebble
Granite, mainly quartz, feldspar, and dark mica/amphibole
AI-generated identification · may be incorrectCoarse-grained, mottled cream-white and black, with a dull to slightly vitreous luster; Mohs hardness about 6–7. Its interlocking crystals have no consistent cleavage as a whole, though feldspar and mica do.
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Physical properties
Coarse-grained, mottled cream-white and black, with a dull to slightly vitreous luster; Mohs hardness about 6–7. Its interlocking crystals have no consistent cleavage as a whole, though feldspar and mica do.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic plutonic events; this specimen appears naturally rounded or tumbled.
Uses & applications
Used widely as construction stone, countertops, monuments, aggregate, and landscaping material; small polished pieces are inexpensive collectibles.
Geological facts
The pale areas are likely feldspar and quartz, while black grains are biotite mica or hornblende. Exact identification would require a close-grained examination or mineral tests.
Field identification & locations
Identify granite by its visibly interlocking, speckled crystals and lack of layering or foliation; common worldwide, especially in continental mountain belts. A hand lens and glass-scratch test can help distinguish its minerals.
