In the deepest region of the Earth's mantle, just above the core, much of the material consists of crystals of magnesium oxide. In larger rocky exoplanets called super-Earths, the higher pressures in the lower mantle may drive magnesium oxide to transform into a new high-pressure crystal structu...
Source: [Phys.org](https://phys.org/news/2026-10-mineral-planets-reveals-lesson.html)