Materials; Supplementary Figure \[fig:phases\]) for hypothetical planetary compositions derived from two samples of stellar compositions. The first includes 1063 FGK stars from @Adib12, which represent thin and thick-disk stars with a metallicity range from -0.8 $<$ \[Fe/H\] $<$ 0.6, over 100 of which are known to host (mostly gas-dominated) planets. Of this first sample, we thermodynamically model the composition and buoyancy of a subset of 609 stellar compositions that are within the internally consistent MELTS database [@Ghio02], 57 of which are known to host planets. We find a chemical buoyancy ($F_c$) of these systems ranges from $-7.5*10^{12}$ N m$^{-1}$ (sinks) to $4.0*10^{12}$ N m$^{-1}$ (floats) while our model Earth produces buoyancy force of $\sim-2.0*10^{12}$ N m$^{-1}$ (Figure \[fig:histogram\]).

The second sample of stellar compositions comes from the Apache Point Observatory Galactic Evolution Experiment [APOGEE, @Wils10; @Maje15], which is part of the Sloan Digital Sky Survey IV [SDSS-IV; @Blan17]. From the public APOGEE Data Release 13 [DR13, @Alba16], we selected the stars known to host small planets (R$_{\rm {p}}$ $\leq$1.6 R$_{\oplus}$) from the *Kepler* transiting planet survey, totaling 123 stars with a metallicity range from -0.54 $<$ \[Fe/H\] $<$ 0.36. Of these, we thermodynamically model the composition and buoyancy of a 