Unakite is a metamorphic rock that forms when granite (an igneous rock) is altered by hydrothermal metamorphism. During metamorphism, plagioclase in the granite is replaced by epidote to produce a rock composed primarily of green epidote, pink orthoclase, and clear to milky quartz. Unakite can also contain minor amounts of magnetite, chromite, ilmenite, apatite, zircon, and other minerals.

Unakite is found in the deformed rocks of convergent plate boundaries where deeply formed granites have been metamorphosed and exposed by weathering and erosion. It occurs where igneous intrusions have delivered the hydrothermal fluids that altered the granite.