Compositional Diversity of Rocky Exoplanets

To test whether exoplanets are similar to Earth, knowledge of their host star composition is essential. Stellar elemental abundances and planetary orbital data show that the ~5,000 known minerals, exoplanetary silicate mantles contain mostly olivine, orthopyroxene, clinopyroxene, ± quartz magnesiowüstite at extremes, while wholly exotic mineralogies unlikely. Understanding geology requires a better marriage geological insights astronomical data. The study like mirror: it reflects our incomplete understanding Earth neighboring planets. New geological/planetary experiments, informed by exoplanet studies, needed for effective progress.