igneous
Granite
Coarse-grained felsic intrusive rock, chiefly quartz, alkali feldspar, plagioclase, and mica (biotite/muscovite).
AI-generated identification · may be incorrectTypically 6–7 Mohs; speckled white, gray, pink, and black appearance, vitreous quartz and feldspar luster, interlocking crystals, and no cleavage as a whole. The specimen shows a granitic texture, possibly slightly weathered or gneissic.
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Physical properties
Typically 6–7 Mohs; speckled white, gray, pink, and black appearance, vitreous quartz and feldspar luster, interlocking crystals, and no cleavage as a whole. The specimen shows a granitic texture, possibly slightly weathered or gneissic.
Formation & geological history
Forms when silica-rich magma cools slowly deep in the continental crust, allowing large crystals to grow; commonly Precambrian to Phanerozoic in age and later exposed by uplift and erosion.
Uses & applications
Widely used for building stone, countertops, monuments, paving, aggregate, and architectural cladding; attractive polished pieces are collectible but usually inexpensive.
Geological facts
Granite’s visible crystals are a record of slow underground cooling. Dark bands or aligned minerals may indicate deformation into granitic gneiss or a related granodiorite.
Field identification & locations
Identify it by coarse interlocking quartz-feldspar crystals and black mica, unlike fine-grained volcanic rhyolite. Common in continental mountain belts worldwide, including the Sierra Nevada, Appalachians, and Scandinavian Shield.
