: Earth’s magnetic field originates in the planet's core from the churning of liquid iron. However, what would have powered such a geodynamo billions of years ago in the newly formed Earth was not known. Now two different research groups have proposed that the process may have been driven by minerals crystallizing out of the molten Earth. However, they disagree on which mineral. At the fall meeting
of the American Geophysical Union in San Francisco, Kei Hirose of the Tokyo Institute of Technology says the mineral was silicon dioxide; David Stevenson of Caltech says magnesium oxide.