The scientists infer that late in the magma - ocean crystallization, iron - rich pyroxene and ilmenite, which formed late and at the crust - mantle boundary, might have begun to sink, and early - formed magnesium - rich olivine might have begun to rise. (sciencedaily.com)
Humayun's team analyzed rock pieces rich in pyroxene and feldspar — minerals that would have been among the first to settle out of a cooling magma chamber. (science.sciencemag.org)