Mineral systems different from bridgmanite. Same as Figure 2(b) but for other mineral density models. (a) Akimotoite system (L. Stixrude & C. Lithgow-Bertelloni 2024) as a proxy for Mars’s lower mantle. (b) Pyroxene system (T. J. B. Holland & R. Powell 2011) as a proxy for Mars’s upper mantle. Earth’s data in panel (a) are the same as in Figure 2 (omitted in panel (b) for clarity). For further details, see text.