Beneath the surface oceans, rivers, and lakes that define Earth's hydrology, a single mineral phase in the transition zone may hold a volume of water that dwarfs every drop on the planet's face.
The freshwater that defines life on this planet — every river system, every Great Lake, every reservoir, every glacial meltwater pond — accounts for a vanishingly small fraction of the water Earth actually contains. The largest reservoir is not at th... [9426 chars]