What specific mineral is identified as key to holding water in the transition zone?
Answer
Ringwoodite
Ringwoodite is the key mineral; it is a high-pressure polymorph of olivine that requires immense pressure to form and traps water within its composition.

Related Questions
Where is this vast, hidden reservoir of water located deep within the Earth?In what state is the water found in this deep reservoir?What specific mineral is identified as key to holding water in the transition zone?What scientific observation first suggested the presence of substantial deep water?What percentage of water by weight can ringwoodite in the transition zone hold?How is the deep water reservoir conceptually different from surface oceans?What geological process allows this deep water to potentially move over millions of years?What is a major implication of this deep water storage on planetary geology?Which laboratory or facility is mentioned in connection with confirming the theoretical capacity of ringwoodite to hold water?When visualizing the deep reservoir, what is the most significant difference from the common perception of an 'ocean'?