igneous
Rounded granite pebble
Granite; primarily quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled gray rock with quartz/feldspar and dark biotite or amphibole; Mohs hardness about 6–7, vitreous to dull luster, and no prominent cleavage as a whole. The smooth shape indicates water or abrasion rounding.
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Physical properties
Coarse-grained, speckled gray rock with quartz/feldspar and dark biotite or amphibole; Mohs hardness about 6–7, vitreous to dull luster, and no prominent cleavage as a whole. The smooth shape indicates water or abrasion rounding.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic mountain-building events. This specimen was likely weathered from an outcrop and transported by a stream, beach, or glacial deposit.
Uses & applications
Used widely as dimension stone, countertops, monuments, crushed aggregate, and landscaping stone; ordinary pebbles have minimal commercial value.
Geological facts
Its visible interlocking crystals distinguish it from basalt, which is typically dark and fine-grained. Exact identification would be improved by a fresh broken surface or a close-up examination.
Field identification & locations
Common in continental shields, mountain belts, river gravels, beaches, and glacial till worldwide. Look for visible light quartz, blocky feldspar, and dark mica flakes in a crystalline mosaic.
