Magma is molten or partially molten rock beneath the Earth's surface. When
magma erupts onto the surface, it is called lava. Magma typically consists of
a liquid portion (often referred to as the melt); a solid portion made of
minerals that crystallized directly from the melt; solid rocks incorporated
into the magma from along the conduit or reservoir, called xenoliths or
inclusions; and dissolved gases. Magma collects inside a volcano's magma
chamber before it erupts (see diagram).
Left: Magma from the belly of Kilauea in Hawaii collects as
it flows out to the Pacific Ocean.