Granite

Coarse-grained felsic intrusive igneous rock of quartz, alkali feldspar, and plagioclase forming continental crust.

Specifications & Metrics

type: Igneous Rock
composition: Quartz (20–60%), alkali feldspar (35–90% of feldspars), plagioclase, and biotite/muscovite mica
texture: Phaneritic (coarse-grained interlocking crystals), occasionally porphyritic
silica content: ~72 wt% SiO₂ (felsic)
density: 2.65–2.75 g/cm³
tectonic setting: Continental crust batholiths, plutons, and convergent orogenic belts

Granite solidifies slowly kilometers beneath the surface from silica-rich (~72 wt% SiO₂) felsic magmas, allowing quartz, potassium feldspar, sodium plagioclase, and mica crystals to grow large enough to be seen with the naked eye.
Lower in density (~2.65–2.75 g/cm³) than mafic oceanic rocks, granitic batholiths and granitoid basement complexes provide the buoyant foundation of Earth's continental crust.
Geologists classify granites by their magma source into I-type (melted meta-igneous lower crust along subduction arcs), S-type (melted aluminum-rich metasedimentary rocks in continental collisions), and A-type (anorogenic rift and hotspot plutons).