igneous
Granite pebble
Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica
AI-generated identification · may be incorrectVisible interlocking grains of pale feldspar and quartz with dark mica or amphibole give it a speckled pink, gray, and black appearance. Hardness is about 6–7 Mohs; luster is mostly vitreous to dull, with no consistent cleavage at the rock scale.
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Physical properties
Visible interlocking grains of pale feldspar and quartz with dark mica or amphibole give it a speckled pink, gray, and black appearance. Hardness is about 6–7 Mohs; luster is mostly vitreous to dull, with no consistent cleavage at the rock scale.
Formation & geological history
Magma cooled slowly underground, allowing crystals to grow; granite bodies form in continental crust over geologic time, commonly hundreds of millions to billions of years old. The rounded shape likely results from weathering and transport.
Uses & applications
Granite is widely used as building and paving stone, countertops, monuments, and decorative aggregate. This small pebble has little commercial value but may be kept as a collection specimen.
Geological facts
Granite’s quartz and feldspar grains are usually visible without magnification, distinguishing it from fine-grained volcanic rocks such as rhyolite.
Field identification & locations
Look for coarse, interlocking light minerals with scattered dark grains and no layering. Granite occurs worldwide in continental mountain belts and glacial or river gravels.
