igneous
Granite pebble
Granite, chiefly quartz, feldspar, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled gray-white rock with possible dark mica; quartz and feldspar have Mohs hardness 6–7, nonmetallic luster, and irregular fracture. The image is slightly blurred, so exact mineral proportions are uncertain.
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Physical properties
Coarse-grained, speckled gray-white rock with possible dark mica; quartz and feldspar have Mohs hardness 6–7, nonmetallic luster, and irregular fracture. The image is slightly blurred, so exact mineral proportions are uncertain.
Formation & geological history
Intrusive igneous rock formed by slow cooling of silica-rich magma deep in Earth’s crust, commonly during Precambrian to Phanerozoic plutonic events. Weathering and transport rounded this small specimen.
Uses & applications
Widely used as dimension stone, countertops, paving, monuments, aggregate, and landscaping material; ordinary pebbles have negligible jewelry value.
Geological facts
Granite’s visible crystals record slow underground cooling, unlike fine-grained volcanic rocks such as rhyolite. Pink or orange tones typically indicate potassium feldspar.
Field identification & locations
Identify by interlocking visible grains of light quartz/feldspar and dark mica or hornblende, with no layers or foliation; common worldwide in continental crust and stream gravels. A hardness test and fresh broken surface improve identification.
