igneous
Granite fragment
Granite, a coarse-grained felsic intrusive igneous rock composed mainly of quartz, feldspar, and mica
AI-generated identification · may be incorrectTypically hardness 6–7 Mohs, gray with visible interlocking crystals, and a granular texture with vitreous quartz and pearly mica luster; no preferred cleavage as a rock. The specimen appears weathered and may contain biotite or hornblende.
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Physical properties
Typically hardness 6–7 Mohs, gray with visible interlocking crystals, and a granular texture with vitreous quartz and pearly mica luster; no preferred cleavage as a rock. The specimen appears weathered and may contain biotite or hornblende.
Formation & geological history
Formed when silica-rich magma slowly crystallized deep in Earth’s crust, commonly during Precambrian to Phanerozoic continental-mountain-building events. Its exact age cannot be determined from the photograph.
Uses & applications
Widely used for countertops, monuments, building stone, aggregate, and paving; small fragments have minimal jewelry or collector value.
Geological facts
Granite’s visible crystals indicate slow underground cooling, unlike fine-grained volcanic rhyolite. Dark minerals are commonly biotite mica or amphibole.
Field identification & locations
Identify it by its speckled, interlocking quartz-feldspar-mica texture and lack of layering or vesicles; common in continental crust and granite quarries worldwide. A hand lens and hardness/glass-streak tests help confirm it.
