Macrophotograph of granodiorite from the Iffinger massif near Merano, South Tyrol, Italy. Granodiorite is an igneous rock that is closely related to granite, but contains a higher proportion of plagioclase than potassium feldspar. It is found worldwide and makes up 34 percent of the intrusive rocks in the Earth's crust. Granodiorites are formed by the crystallisation of molten rock (magma) within the Earth's crust, mostly at depths of more than two kilometres. This rock was formed about 286 million years ago. Granodiorite contains quartz, plagioclase, orthoclase, and a little biotite. Magnification: x4 when printed at 15 centimetres wide.