text: There may be equilibrium fractionation between coexisting minerals. This would be particularly relevant when considering the formation of planetary bodies early in the solar system. Experiments have aimed to simulate the formation of the Earth at high temperatures using a platinum-iron alloy and an analog for the silicate earth at 1,500 °C. However, the observed fractionation was very small, less than 0.2‰ per atomic mass unit. More experimental work is needed to fully understand this effect.