Magma is molten rock often located inside a magma chamber[?] beneath the surface of the earth. Magma in Earth is a complex high-temperature silicate solution that is ancestral to all igneous rocks, both intrusive and effusive. Magma is under high pressure and sometimes emerges through volcanic vents in the form of lava. It usually contains dissolved gases and water which have never before reached the planet's surface. Magma collects in many separate magma chambers within the Earth's crust, and so may have slightly different compositions in different places.