Mineral Ecology: Chance and Necessity in the Mineral Evolution of Terrestrial Planets

Three factors contribute to the roles played by necessity and chance in determining mineral distribution and diversity at or near the surfaces of terrestrial planets: (1) planetary stoichiometry; (2) crystal chemical characteristics; and (3) the probability of occurrence for rare minerals. Measurements of stellar stoichiometry reveal that stars can differ significantly from the Sun in relative abundances of rock-forming elements, which implies that bulk compositions of some extrasolar Earth-like planets likely differ significantly from those of Earth. The most abundant elements generally have the largest numbers of mineral species, though several elements that mimic other more abundant elements are less likely to form their own species. Statistical analysis of mineral frequency distributions suggests that thousands of plausible rare mineral species await discovery or could have occurred at some point in Earth’s history, only to be subsequently lost by burial, erosion, or subduction. Were Earth’s history to be replayed, and thousands of mineral species discovered and characterized anew, it is probable that at least 25% of those minerals—more than 1000 species—would differ from species known today.