Granite is the most common intrusive rock in Earth’s continental crust, It is familiar as a mottled pink, white, gray, and black stone. It is coarse- to medium-grained. Its three main minerals are feldspar, quartz, and mica, which occur as silvery muscovite or dark biotite or both. Of these minerals, feldspar predominates, and quartz usually accounts for more than 12 percent. Granite crystallizes from silica-rich magmas that are miles deep in Earth’s crust.