In this experiment, we plan to study Fe-Si-C ternary system at high-pressure high-temperature conditions. This system is of significant importance for constraining the composition of the Earth’s inner core as well as of other terrestrial planets. Yet, information on the phase relations in this ternary system at extreme conditions is scarce. The aim of the experiment is to investigate which phases in the iron-rich part of the ternary Fe-Si-C system are stable under conditions relevant to the deep Earth’s interior.