Granite (/ˈɡrænɪt/) is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. Granite forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. Granite is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers.