Granodiorite is an intrusive igneous rock that slowly cools deep underground in magma chambers called plutons. Granodiorite is composed of black biotite, dark-gray hornblende, off-white plagioclase, and translucent gray quartz. It is a product of melting continental rocks near subduction zones, and can be found on continents around the world near active or past plate boundaries. For example, granodiorite rocks can be found west of the San Andreas fault near Monterey, Pacifica, and Point Reyes.
