Evidence for the stability of ultrahydrous stishovite in Earth’s lower mantle

Significance The great abundance of water on Earth’s surface makes it different from other terrestrial planets, and it may be linked to a deep interior water cycle. How water is transported into Earth’s deep interior and in which phases it is held are still a matter of much debate. Stishovite is known as a major component of subducted oceanic basalt, and recent experiments have reported that it can incorporate significant amounts of water in its crystal structure. Here, we show that, at the pressure–temperature conditions of a mantle geotherm, stishovite may be a key phase for transporting water into the deep mantle, providing important information on the water cycle in the deep earth.