Iron meteorites of the solar system are composed of parent cores belonging to the earliest credited bodies of the environment. The cores are formed in two isotopically distinct reservoirs including non-carbonaceous and carbonaceous types in the inner and outer solar system. In a new report now published in Science Advances, Bidong Zhang and a team of scientists in Earth, Planetary and Space Sciences, at the University of California Los Angeles, and the Applied Physics Laboratory of Johns Hopkins University, measured the elemental composition of carbonaceous-iron groups using fractional crystallization modeling to reconstruct bulk compositions and crystallization processes of preceding parent asteroid cores.